The orthogonal experiment of laser spot welding is conducted when the DP590 dual phase steel with 1.5 mm thickness is used as the base material and the welding time, the welding power and the defocusing are taken as variables. The internal morphology of the joints is studied, influences of welding parameters on the static performance of the joint are analyzed, and the morphologies of tensile shear fractures are invesitgated. The results show that, when the welding power is 1800 W, the welding time is 1000 ms and the defocusing is -3 mm, the average peak load of adhesively bonded spot welding joints is the maximal, which is 7529.30 N. The ultrasonic C-scan image of the laser welding joints can be divided into the nugget zone, the cavity zone, the heat-affected zone and the adhesive zone, and the ultrasonic C-scan image can be used to effectively measure the nugget diameter. The influence of the welding power on the tensile and shear properties of the joints is the maximal, that of the welding time is the second, and that of the defocusing is the minimal. With different welding parameters, the failure modes of the joints are interfacial fractures, and the elongated dimples are distributed on the fracture surface of solder joints.