The invention relates to a PWM self-testing method. The method comprises: step one, collecting an outputted PWM current signal and converting the PWM current signal into a square wave signal; step two, collecting a duty ratio of the square wave signal to obtain a PWM output signal recovery value PWMWA and comparing the PWMWA with a PWM output signal front period value PWMPV to obtain a collection comparison difference; and step three, comparing the collection comparison difference with a preset threshold value and outputting a PWM self-testing result based on a comparison result. According to the invention, the real-time performance of PWM detection can be improved effectively; the complexity degree and size of the hardware circuit can be reduced; the PWM detection precision can be enhanced; the application range is wide; and the security and reliability are high.