Abstract: The anti-seismic properties,i.e.the coordination of strength and ductility,sensibility of strain aging,brittleness at low temperature and weldability were systematically investigated for 20MnSiV HRB400 reinforced steel bar with the diameter of 20 mm.Test results showed the DBTT of strain aged steel bars rose,and the anti-seismic properties of the steel bars at low temperature were poor.The C_eq value of the steel bar was slightly high,as a result the weldability should be advaced.The results of microstructure observation showed that the content of micro-alloying elements should be adjusted in order to enhance anti-seismic properties of steel bar.