The invention relates to a high-voltage interface device and system. The high-voltage interface device comprises an optical fiber used for communication, an insulation device used for transmitting ultrasonic waves, a first ultrasonic transducer element arranged at one end of the insulation device, and a second ultrasonic transducer element arranged at the other end of the insulation device, wherein the first ultrasonic transducer element is used for converting input electric power signals into ultrasonic waves and transmitting the ultrasonic waves to the insulation device; the second ultrasonic transducer element is used for converting the ultrasonic waves from the insulation device into electric power signals to be output. According to the high-voltage interface device and system, the adoption of an isolation transformer is avoided, so that the problems that the weight and size of a device are large and cost is increased due to the fact that the isolation transformer is used are avoided.