High-speed rotating gears are generally lubricated by fuel injection. Lubricating oil is driven by high-speed rotating gear, and some lubricants will be excited into oil mist, so that the gears are in the gas-liquid mixed environment. In this paper, the computational fluid dynamics model of the fuel injection cooling process is established based on the gear heat transfer behavior under the fuel injection condition. The influence of different fuel injection parameters on the liquid-solid two-phase convective heat transfer coefficient is obtained. On this basis, the accurate boundary conditions of gear temperature field calculation are analyzed by studying the heat transfer behavior of high speed gear injection lubrication. The calculation model of gear temperature based on fuel injection lubrication is established, and the temperature field distribution of gear is obtained. Finally, the gear injection cooling test stand is set up, and the accuracy of the calculation method is verified by comparing the measured value of the tooth surface temperature with the calculated value.