Many major accidents in domestic and foreign power grids were caused by cable defects, causing huge economic losses and adverse social impacts. At present, the three main tests for cable testing are withstand voltage test, dielectric loss measurement and partial discharge measurement, which require different equipment for testing, which is low in efficiency and time-consuming. Among them, the very-low frequency method is suitable for the withstand voltage test, and the damped oscillatory wave method is suitable for the measurement of dielectric loss and partial discharge. This paper is based on very-low frequency cosine square wave and damped oscillatory wave technology, implements technology integration, and realizes the three-in-one detection of withstand voltage, dielectric loss, and partial discharge for cable.