The system resonance is difficult to maintain in the machining process of ultrasonic combined electrochemical machining, because a manual adjustment of ultrasonic frequency generates test error. This problem can be solved by constructing and perfecting the online parameter detection and control system of ultrasonic combined electrochemical machining. This study build the data acquisition system of the signal parameters by selecting a variety of high speed and high precision sensor, vibration displacement of tool electrode in the process of ultrasonic power and pulse power output voltage, EDM electrode current of online detection, and the use of PCI-1706U data acquisition card; designs the vibration displacement signal of laser displacement sensor detection as the chopper voltage control signal of pulse power supply; uses digital potentiometer to replace the original mechanical potentiometer, ultrasonic power supply, the output resistance of the digital potentiometer controlled by MCU STM32 communication. By the tools of Visual C++ 6.0 design of compound ultrasonic EDM detection and control system software, through the data acquisition card library programming, data acquisition, processing, display functions including the signal detection module design parameters; design the control software module through the serial port. Compared with the manual control parameters, the control system of ultrasonic combined electrochemical machining test can guarantee precision, improve the process stability and machining efficiency.