The present invention provides a multifunctional fault-signal simulating device. The multifunctional fault-signal simulating device comprises a fault simulation main circuit module, a control module used for controlling a fault simulation circuit and a power supply module. The power supply module supplies power to the main circuit module and a control circuit, and the main circuit module is divided into two parts of a general function module and a bad contact function module, according to the functions In a short circuit function module, the control module sends out a control instruction to control the open and closing of a relay, thereby selecting the different fault access signals. In the bad contact function module, a fault simulating device is accessed in a controlled system to control the closing of a MOS transistor by the PWM and generate a bad contact effect, thereby simulating a bad contact fault. The multifunctional fault-signal simulating device of the present invention enables the coverage rate that the fault simulating device simulates the faults to be increased, and can test a control system more comprehensively.