This paper investigates the lubrication heat transfer mechanism in a multilevel gearbox using the lattice Boltzmann method (LBM) combined with large eddy simulation (LES). The study focuses on a conical-cylindrical two-stage gearbox, where the LBM D3Q27 velocity model is used to simulate the flow field and analyze the fluid motion law in a closed space. The effects of different rotational speeds, steering methods, and lubricant properties on the thermal flow field and heat dissipation efficiency are explored. The results show that the lubricant distribution in the gear meshing area is uniform and thoroughly lubricates the gears, with the temperature rise increasing significantly as the rotational speed and gear steering change. The dynamic viscosity and thermal conductivity of the lubricant also significantly affect the heat dissipation, with higher thermal conductivity leading to better heat dissipation efficiency. The study provides valuable insights for optimizing the thermal performance and design of gear transmission systems.This paper investigates the lubrication heat transfer mechanism in a multilevel gearbox using the lattice Boltzmann method (LBM) combined with large eddy simulation (LES). The study focuses on a conical-cylindrical two-stage gearbox, where the LBM D3Q27 velocity model is used to simulate the flow field and analyze the fluid motion law in a closed space. The effects of different rotational speeds, steering methods, and lubricant properties on the thermal flow field and heat dissipation efficiency are explored. The results show that the lubricant distribution in the gear meshing area is uniform and thoroughly lubricates the gears, with the temperature rise increasing significantly as the rotational speed and gear steering change. The dynamic viscosity and thermal conductivity of the lubricant also significantly affect the heat dissipation, with higher thermal conductivity leading to better heat dissipation efficiency. The study provides valuable insights for optimizing the thermal performance and design of gear transmission systems.