Fishtail Divertor (FTD), a new divertor concept, is a significant research object of EAST tokamak divertor system. To meet the requirements of sinusoidal current precision and variable frequency, the combination of Inductance and Capacitance (LC) series resonance theory and high-frequency Pulse Width Modulation (PWM) technology is put forward. A sine wave power supply with multi frequency points (10-3800 Hz) and current up to 8000 A is developed. The FTD power supply adopts DC switching power technology, Sinusoidal Pulse Width Modulation (SPWM) technology and LC series resonance theory. The operating points of output current include 10 Hz at 8000 A, 20 Hz at 6000 A, 30 to 110 Hz at 5000 A and 1300 Hz to 3800 Hz at 2400 A. The output current accuracy can reach 5% by the current feedback and frequency feedback control strategy. The test results demonstrate that the FTD power supply can meet the system requirements, and it can provide reference for the design of other divertor power supply.