The invention discloses a power supply circuit. The power supply circuit is used for supplying power to an electric spindle spinning frame. The power supply circuit is coupled with a three-phase powergrid, the power supply circuit includes a rectifier bridge and a driving circuit, the driving circuit includes a direct current/direct current converter, a first driving circuit and a first control chip, the input end of the rectifier bridge is coupled with the three-phase power grid, the output end of the rectifier bridge is coupled with the first input end of the direct current/direct current converter, the output end of the direct current/direct current converter is connected with the electric spindle spinning frame, and the output end of the first driving circuit is coupled with the second input end of the direct current/direct current converter. Through the connection mode, the size and weight of a power supply system can be decreased, the material loss is reduced, and meanwhile, theefficiency of power supply can be effectively improved.