Abstract: Using ABAQUS finite element software, a finite element model was established on magnesium/titanium dissimilar metal cold metal transfer lap joint to numerically simulate the temperature distribution. The simulated temperature field was verified by experimental results. The variation of temperature field and microstructure at specified location of the joint were compared at different wire feed speeds. The results show that the distribution of temperature field was asymmetric on magnesium and titanium sides. At two locations with the same distance from the weld center, the temperature rose rapidly on magnesium side, a higher peak temperature in Mg sheet was reached than that in Ti sheet, and the rate of decline was also fast. As the wire feed speed increased, the peak temperature became higher and reached the molten temperature of titanium sheet, then the amount of molten Ti increased, finally sound Mg/Ti interface formed.