This article presents a novel microscopic bubble/precipitate traffic system (MBPTS) that enables stable seawater reduction electrocatalysis at industrial-level current densities. The system is implemented through a honeycomb-type 3D cathode structure, which efficiently releases small-sized H₂ bubbles to repel Mg²⁺/Ca²⁺ precipitates. This design allows for state-of-the-art alkaline seawater reduction performance, with 1000-h stable operation at −1 A cm⁻² and high anti-precipitation ability. A flow-type electrolyzer based on this cathode operates stably at 500 mA cm⁻² for 150 h in natural seawater, achieving near-100% H₂ Faradic efficiency. The estimated cost of hydrogen production (~1.8 US$/kgH₂) is even cheaper than the US Department of Energy’s goal price (2 US$/kgH₂). Seawater electroreduction is attractive for future H₂ production and intermittent energy storage, but has been hindered by aggressive Mg²⁺/Ca²⁺ precipitation at cathodes. The MBPTS system effectively prevents this by creating a uniform distribution of H₂ bubbles that repel precipitates without interruption. The cathode's 3D honeycomb structure allows for efficient gas transport and prevents precipitation buildup, leading to long-term stability and high performance. The system also demonstrates superior anti-precipitation ability and high electrocatalytic activity, making it a promising solution for seawater electrolysis. The article highlights the development of a NiCoP-based 3D cathode with a honeycomb-like porous carbon framework, which enables efficient H₂ evolution and anti-precipitation. The cathode's structure supports the growth of nanoneedle-like NiCoP, which enhances catalytic activity and stability. The cathode's performance is evaluated in both alkaline and natural seawater, showing high efficiency and stability under industrial conditions. The system's ability to repel Mg²⁺/Ca²⁺ precipitates is confirmed through various experiments, including in situ Raman spectroscopy and elemental analysis. The study also investigates the bubble behavior and transport in seawater reduction, demonstrating that the MBPTS system effectively repels precipitates by creating a uniform distribution of H₂ bubbles. The system's performance is further validated through flow-type electrolysis experiments, showing stable operation at industrial current densities and high H₂ production efficiency. The cathode's unique architecture and design enable efficient gas transport and anti-precipitation, making it a promising solution for seawater electrolysis. The study provides a comprehensive understanding of the MBPTS system's performance and potential for industrial applications.This article presents a novel microscopic bubble/precipitate traffic system (MBPTS) that enables stable seawater reduction electrocatalysis at industrial-level current densities. The system is implemented through a honeycomb-type 3D cathode structure, which efficiently releases small-sized H₂ bubbles to repel Mg²⁺/Ca²⁺ precipitates. This design allows for state-of-the-art alkaline seawater reduction performance, with 1000-h stable operation at −1 A cm⁻² and high anti-precipitation ability. A flow-type electrolyzer based on this cathode operates stably at 500 mA cm⁻² for 150 h in natural seawater, achieving near-100% H₂ Faradic efficiency. The estimated cost of hydrogen production (~1.8 US$/kgH₂) is even cheaper than the US Department of Energy’s goal price (2 US$/kgH₂). Seawater electroreduction is attractive for future H₂ production and intermittent energy storage, but has been hindered by aggressive Mg²⁺/Ca²⁺ precipitation at cathodes. The MBPTS system effectively prevents this by creating a uniform distribution of H₂ bubbles that repel precipitates without interruption. The cathode's 3D honeycomb structure allows for efficient gas transport and prevents precipitation buildup, leading to long-term stability and high performance. The system also demonstrates superior anti-precipitation ability and high electrocatalytic activity, making it a promising solution for seawater electrolysis. The article highlights the development of a NiCoP-based 3D cathode with a honeycomb-like porous carbon framework, which enables efficient H₂ evolution and anti-precipitation. The cathode's structure supports the growth of nanoneedle-like NiCoP, which enhances catalytic activity and stability. The cathode's performance is evaluated in both alkaline and natural seawater, showing high efficiency and stability under industrial conditions. The system's ability to repel Mg²⁺/Ca²⁺ precipitates is confirmed through various experiments, including in situ Raman spectroscopy and elemental analysis. The study also investigates the bubble behavior and transport in seawater reduction, demonstrating that the MBPTS system effectively repels precipitates by creating a uniform distribution of H₂ bubbles. The system's performance is further validated through flow-type electrolysis experiments, showing stable operation at industrial current densities and high H₂ production efficiency. The cathode's unique architecture and design enable efficient gas transport and anti-precipitation, making it a promising solution for seawater electrolysis. The study provides a comprehensive understanding of the MBPTS system's performance and potential for industrial applications.