This paper analyzes of various partial discharge types and partial discharge detection methods, for high voltage switchgear partial discharge online monitoring. Among these detection methods, UHF and ultrasonic detection method are mainly studied. Based on this, an acoustic and electric combined online monitoring system is designed. The system uses a peak detection chip to detect peak voltage of partial discharge signal, which can increases the controllability of the system, and uses FPGA chip to deal with UHF signals and ultrasonic signals. It shows good real-time performance and fast response characteristics. The system can quickly deal with signals, and accurately identify the type of partial discharge, in order to ensures the safe operation of the switchgear.