Abstract: Four channel steel reinforced concrete beams and 1 reinforced concrete beam are tested to study the mechanical behaviors of channel steel reinforced concrete beam ( CSRCB) under pure torque． The failure process and modes of the specimens are observed，the effects of concrete strength，stirrup form and lace bar form etc on the torsional bearing capacity of the specimens are discussed． It is shown that the steel ratio has no significant effect on the cracking torque of the section，but the channel steel can improve the torsional capacity，stiffness and ductility of the beam obviously． The calculating formula for cracking torsional torque and ultimate torsional capacity of the CSＲCB member are also proposed．