Abstract: Dual phase steel spot weld characteristic was investigated.And then fatigue strength of dual phase steel lap-shear spot weld was tested, the data for spot weld fatigue curve were obtained. The fatigue crack propagation path and failure modes of specimens were also studied.On the basis of crack propagation path local equivalent stress intensity factor k_eq was applied to analyze the fatigue life of dual phase steel spot weld.The test result indicated that k_eq was an effective parameter to predict spot weld fatigue strength prediction, which can correlate fatigue life of spot weld specimens with different thickness and weld nugget size.