The problem for adjusting heating current in Electric Hot Machining is how to detect the change of cutting condition. In this paper, Cutting state resistance has been proposed as a state parameter for self-adjusting heating current in EHM. An investigation on the relationship between this parameter and cutting conditions has been carried out. The experimental results show that cutting state resistance can rapidly respond the change of cutting state and optimum control of heating current can be realized in electric hot machining by means of detecting this resistance.