The invention discloses a portable partial discharge ultrasonic cloud detection device, which comprises an ultrasonic sensor, a temperature sensor, a humidity sensor, an atmospheric pressure sensor, a signal processing module, a wireless network device, a display and an earphone. The sensor transmits the signal to the signal processing module, and the processed signal is transmitted to the cloud server through the wireless network device, and the signal is subjected to anti-interference processing and characteristic parameters are extracted and stored in the partial discharge signal characteristic database. For analysis, the operator monitors the sound in the earphone and makes a diagnosis based on the results of the cloud server. The diagnosis result is displayed on the monitor, and the device detects and alarms at the same time. The invention uses the data analysis, processing and storage capabilities of the cloud detection principle to detect the partial discharge in the equipment early and prevent the occurrence of major accidents through online monitoring or inspection of the partial discharge of the high-voltage equipment.