To meet the needs of programmed remote control operation of disconnectors, this paper establishes mathematical model for impedance identification of the opening and closing position of the disconnector, and analyzes the mapping relationship be-tween the spatial position of the movable contact of the disconnector and the system reflection impedance. Establish the pressure deformation sensing MEMS of the moving contact of the disconnector, derive the theoretical model of small deflection thin plate applicable to MEMS, and determine the specification size and deformation threshold of MEMS. Construct the peak characteristics of "increased reflection impedance in the rotation process - decrease reflection impedance in the deformation process" of the disconnector from opening to closing. Construct the time-domain fusion comprehensive criterion of the first criterion of the opening and closing position of the disconnector, the auxiliary contact and the second criterion of non-homogeneous peak im-pedance. Through the analysis of examples, the experiment verified the significance of the peak impedance of the non-homogeneous second criterion, and the reliability of the comprehensive criterion of the time domain fusion of the first criterion and the second criterion. A non-homologous double confirmation method with high precision, low cost, high reliability and wide applicability is provided for the opening and closing position of the disconnector.