Abstract: In order to study the application of resistance spot welding in advanced high strength steel, MS1400 and DP980 with thickness of 1.2 mm are used for spot welding experiments. The experimental results show that there are three failure modes which include the interface fracture, the pullout fracture and the part of pullout fracture. The better parameters are obtained by adjusting the welding time and welding process parameters. The microstructures of the heat affected zone on both sides of MS1400 and DP980 and the fusion zone are analyzed under the optimal parameters. The evolution of each region is related to the microhardness distribution curve.