Abstract: The fast Zpinch phenomenon and the physics of fast Zpinch are introduced in this paper. And the factors which influence the instability of fast Zpinch are simply analysed. The PSPICE circuit analyses are very useful for the design of the pulsed power. In the paper, the PSPICE circuit analyses is used for solving the thin annular shell of imploding wire array, and simultaneously with the pulsed power system. From the circuit analyses, some Zpinch physics parameters ( pinch time, velocity, radius, et al) are given simultaneously with the pulsed power ( current and voltage).