Switching diodes are a kind of the most widely used in microwave control circuits of control devices, and it can obtain the good performance of short circuit and open circuit. The thickness of I region has an important effect on the characteristics of PIN diodes device.In this paper, the structure of InPbase PIN switching diode device is modeled bySilvaco TCAD software, and then analyze the influence of different I region thickness on the current and voltage characteristics of the diode and obtain the optimal value. Usingcompound semiconductor materials epitaxy and device technology platform,InPbase PIN switching diode device is prepared, and the test results of DC characteristics show that, the turn on voltage of PIN switching diode is 0.525 V, and the reverse breakdown voltage is larger than 12 V, which has laid a foundation for further realizing the millimeter wave switching circuits.