Dual phase (DP) steel is increasingly utilized in automotive industry to match the requirement of both performance and lightweight of autobody for economical and ecological considerations. Most of autobody structures are manufactured by stamping process which imports prestrain effects into original material and alters its static and cyclic mechanical behaviors. In this study, mechanical behavior of prestrained DP steel was researched. Firstly, microstructure of commercial DP steel with different prestrain levels was examined with optical microscope of 500X magnification. Then, static tensile experiments and strain-controlled fatigue experiments were carried out at room temperature. Test results of differenet prestrain levels were compared. Static stress-strain relationship and local strain-life model were determined using linear regression method. Furthermore, fatigue performance and notch fatigue resistance capability were compared with prestrain level based on Neuber factor. Finally, explanation of the change with prestrain was presented with crack closure theory.