In order to study the impact of different injection parameters (number of injection holes, injection angle, injection advance angle) on the in-cylinder combustion and emission performance of diesel engine under low temperature environment, a three-dimensional model of a certain type of direct-injection diesel engine was established, and combustion simulation was carried out for different injection parameters of diesel engine under low temperature environment. The results show that the fuel injection parameters influence the fuel injection duration, the fuel spatial distribution, the swirl in the pit at the bottom of the combustion chamber, the penetration distance and diffusion angle of the fuel spray, the fuel-air mixing time and mixing effect, which will affect the combustion and emission performance of the diesel engine; The diesel engine can obtain the best power performance under low temperature environment when the number of injection holes is 8, the injection angle is 150°, and the injection advance angle is 18 ℃[KG-*7]A BTDC (before top dead center). The mechanism of the influence of injection parameters on diesel engine combustion and emission under low temperature environment has been obtained, which provides some reference for the optimization of diesel engine injection parameters under low temperature environment.