As a kind of high quality metal material, magnesium is widely used in various fields. There is little research on the molecular level of magnesium. In this paper, the effect of temperature on the properties of single crystal magnesium at a tensile rate of 10^10s^-1 was studied by using molecular dynamics simulation method, and stress-strain analysis, potential energy strain analysis, common neighbor analysis, dislocation density analysis and other operations were performed on the results. The results show that the peak tensile strength of monocrystalline magnesium decreases with the increase of temperature, and the corresponding strain value of each peak point decreases with the increase of temperature. HCP before the peak stress appears first converted into Other structures without dislocation, after the peak stress in the FCC, BCC structure appeared at the same time produce dislocation, dislocation mainly for 1/3<-1100> dislocation and unknown dislocation structure, the corresponding crystal structure transformation and the generation of dislocation about lag strain values of stress peaks around 0.45%, and the effects of temperature on lag value is not big, crystal structure transformation and the generation of dislocation and with the increase of temperature in advance.