In order to improve the start-up performance of traditional gasoline engines and reduce the fuel consumption rate in the start-up phase,this study attempted to make the gasoline engine startup successfully under the condition of equival enceratio by adding hydrogen. The mixtured is tribution and ignition of hydrogen-gasoline engines under the condi- tion of equival enceratio were studied by numerical simulation,in the hope of finding a better hydrogen-gasoline injection solution.First,a 3D numerical model of hydrogen-gasoline engine under cold start condition was constructed,and the valve movement law and the re- lationship between fuel injection quantity and hydrogen injection quantity were calibrated. Then,the 3D numerical model was tested and verified,and the experimental results were in good agreement with the calculated results.Finally,under the condition of equivalence ratio,the simulation calculation of ignition under cold start condition was carried out.The research results show that under the condition of equivalence ratio,adding hydrogen can significantly accelerate the diffusion speed of the mixture compared with pure gasoline engines,so that the mixture can be evenly distributed in the cylinder faster.When pure gasoline is used in start-up,the first cycle ignition is difficult,while adding hydrogen can achieve the first cycle ignition.But when the amount of hydrogen is toolarge,pre-ignition will occur.Adding hydrogen can significantly reduce HC and CO emission in the cold start phase.