The organic static induction transistor (OSIT) fabricated with organic semiconductor material copper-phthalocyanine(CuPc)is discussed in the paper. It has Schottky Gate electrode and sandwich structure of Au/CuPc/Al/CuPc/Au/glass. The operation mechanism of the device is studied on the physical model with practical parameters. Potential distribution and field intensity distribution in the conduction channel are computed by using finite-element method. By processing static experimental data with some mathematic tools,the V- I expression of CuPc/Al Schottky Gate is obtained and it is verified that OSIT has insaturation current property along with the increase of Drain bias voltage. By using AC small signal circuit model and appropriate numerical simulation method, the dynamic operating characteristics are investigated, and some influenced factors are analyzed.