If the intermediate frequency current is modulated by the low frequency current, the current whose amplitude and frequency change with the amplitude and frequency of the low frequency current is called modulated intermediate frequency current. The method of using this current to treat diseases is called modulated intermediate frequency electrotherapy, while another standard intermediate frequency therapeutic instrument uses 2- 10KHz current for treatment, and the power is generally tens of watts. The low-intermediate frequency therapeutic instrument widely used in China in recent 20 years is based on the original low-frequency therapeutic instrument (electroacupuncture instrument), and some intermediate frequency components are appropriately introduced.