JTAG-based fault injection of core devices is a real-time, easy-to-control, non-destructive fault injection method. However, JTAG signal voltages of core devices produced by various chip manufacturers are different, and JTAG instruction codes are also different. Currently, there is a lack of generic JTAG-based fault injection device and method. A general fault injection system based on JTAG and a fault injection method are proposed for this problem. The system consists of a host computer, a serial port module, an Microcontroller Unit controller and a JTAG level conversion module, and the system can perform fault injection on all JATG control units manufactured by different manufacturers according to the IEEE 1149.1-1994 boundary scan technology standard.