This study introduces a novel droplet microfluidic chip designed to enhance single-cell encapsulation in droplets by overcoming the trade-off between cell suspension density and on-chip focusing performance. The chip features a double spiral focusing unit, a flow resistance-based sample enrichment module, and a crossflow droplet generation unit. The sample enrichment module allows for adjustable flow resistance by changing the number of serpentine units, enabling the removal of excess water phase and optimizing cell density. Numerical simulations and experiments at different flow rates (40, 60, 80 μL/min) demonstrated successful focusing of beads and cells, with encapsulation rates of 79.2% and 72.2%, respectively. The YOLOv8n-based droplet detection algorithms confirmed the high efficiency of single-cell and bead encapsulation. The study highlights the potential of this on-chip sample enrichment approach for various applications in single-cell analysis and microfluidics.This study introduces a novel droplet microfluidic chip designed to enhance single-cell encapsulation in droplets by overcoming the trade-off between cell suspension density and on-chip focusing performance. The chip features a double spiral focusing unit, a flow resistance-based sample enrichment module, and a crossflow droplet generation unit. The sample enrichment module allows for adjustable flow resistance by changing the number of serpentine units, enabling the removal of excess water phase and optimizing cell density. Numerical simulations and experiments at different flow rates (40, 60, 80 μL/min) demonstrated successful focusing of beads and cells, with encapsulation rates of 79.2% and 72.2%, respectively. The YOLOv8n-based droplet detection algorithms confirmed the high efficiency of single-cell and bead encapsulation. The study highlights the potential of this on-chip sample enrichment approach for various applications in single-cell analysis and microfluidics.