The invention relates to the field for detecting an instant surge pulse of a microwave oven in starting, and particularly to a device for detecting the instant surge pulse of the microwave oven in starting. The device comprises a photoelectric isolator, a waveform finishing device, a waveform display device and an isolated power supply. The photoelectric isolator is connected with one end of the waveform finishing device through a lead. The waveform finishing device is connected with the waveform display device through a lead. One side of the waveform display device is connected with the isolated power supply. One side of the photoelectric isolator is connected with a high-voltage component detecting point of the microwave oven through a lead. One side of the photoelectric isolator is connected with a grounding line through a lead. The high-voltage component detecting point of the microwave oven can be a front end A of a high-voltage capacitor or a back end A of the high-voltage capacitor in a high-voltage component circuit of the microwave oven. The device is advantageous in that simple and ingenious designing is realized; and a captured instant high-voltage surge pulse waveform is displayed and stored through the methods of dynamic sampling, high-voltage signal insulation, high-speed detection, high-speed detection, high-speed record, etc.