The influence laws of strain rate on the mechanical properties and plastic characteristics of different materials are quite different. The interstitial free steel DX54D+Z was selected as the research object to analyze the influence of high strain rate on the mechanical properties and microstructure characteristics. The mechanical properties of IF steel at seven strain rates in the range of 0.001-1000 s-1 were tested by the hydraulic servo high-speed tensile testing machine. The fracture morphology feature and micro-structure of each sample were analyzed. The results show that DX54D+Z steel exhibits a significant positive strain rate correlation. With the increasing of strain rate, the material strength is obviously enhanced, the yield-to-tensile ratio remains basically unchanged at about 0.576, and the uniform elongation and elongation after fracture generally show a trend of first increasing and then decreasing. The fracture of each sample presents typical ductile fracture, and the depth and density of dimples increase with the increasing of strain rate. The cracks of sample first initiate at the ferrite grain boundary, as the distance from the fracture increases, the number and density of cracks gradually decrease, and the tensile deformation of ferrite also weakens gradually.