Abstract: The effect of rolling temperature on the microstructure and mechanical properties of Q420 high-performance building steel was studied by Gleeble-3500 thermo mechanical simulator, metallographic and mechanical properties tests.The results show that with the rolling temperature decreasing, the grain sizes of ferrite and pearlite decrease, and the volume fraction of ferrite decreases while the volume fraction of pearlite increases.In addition, the TEM analysis results indicate that with the rolling temperature decreasing, more and finer precipitates are observed. Finally, the mechanical properties of the different rolling temperature samples were analyzed. It is shown that microstructure refinement and more fine carbide precipitation make the samples with the lower rolling temperatures have higher yield strength and tensile strength.