Abstract: Effect of finishing rolling temperature on microstructures and mechanical properties of steel strip for engineering mechanism was studied by means of optical microscopy, SEM, TEM, tensile property testing and impact toughness testing.The results show that tensile strength and yield strength of testing steel decrease and elongation increase with the decrease of finishing rolling temperature.The value of low temperature impact toughness with high finishing rolling temperature is very low, while it increases a lot as finishing rolling temperature decrease.The microstructure of testing steel with high finishing rolling temperature consists of ferrite and a little pearlite, which is inhomogeneous.While with intermediate and low finishing rolling temperatures, the microstructure of it contains ferrite and pearlite, and the ferrite grain is regular.The microstructure of testing steel with low finishing rolling temperature is more homogeneous than that with intermediate finishing rolling temperature.Strip-like or rod-like multicarbides M₃C exist on the grain boundary of ferrites with high finishing rolling temperature.