The invention relates to a device and a method for treating tumors through irreversible electroporation, belonging to the technical field of tumor treatment. The device mainly comprises a square wave pulse generation and measurement system, a signal conversion system, a man-machine communication system, a measurement control system and a power supply system. In the method, the device and a therapeutic electrode are used for treating the tumors through a program. Under the circumstance of no injection of chemotherapeutic drugs, microsecond square wave pulses are applied to tumor tissues, the entire tumor cell is fully damaged, so that the tumor cell dies due to irreversible electroporation, and the harm on the body of a patient caused by the side effect of the chemotherapeutic drugs is radically avoided. The invention has the characteristics of short treatment time, no pain, good treatment effect, high safety, convenient use, simple operation, convenient popularization and application and the like. The device and the method can be widely used for treating the tumors of human and animals, and are especially applicable to human tumor treatment.