Abstract: In the reliability estimation and inspection of existing structures,the working stress state of a RC structure is an important index related with structural behavior,but there was not a reliable testing method by which one can obtain the working stress in a RC structure.After having analyzed the common test methods of working stress briefly,the boring-electrical test method is proposed to test the working stress of RC compression member.The working stress of the RC compression member in existing structures can be calculated through measuring strain change before and after drilling the hole,determining the compressive strength and elastic modulus of concrete through the drilled sample and combining the calculating results of the finite element method.The tested results show that the actual release strains at the edges of the hole agreed well with those of computed by the finite element method,so the boring-electrical test method can be used to test working stress of practical RC compression member.