In this paper ,21 pieces of ribbed rebar 16 in diameter,45 pieces of smooth circle rebar 12 and 8 in diameter and 24 pieces of high strength carbon steel wire s5 in diameter are tested on mechanical behaviors under high temperature.The laws of variation of mechanical behaviors with the temperature are investigated for prestressed steel and non_prestressed steel.The conclusions obtained in this paper are significant for research of the loading capacity of reinforced concrete members under the condition of fire catastrophe.