The invention discloses a rotary ultrasonic machining device based on non-contact energy transfer. The rotary ultrasonic machining device based on non-contact energy transfer comprises a high-speed electric spindle, a primary side assembly fixed to the lower end of the high-speed electric spindle, an ultrasonic knife handle assembly composed of an ultrasonic knife handle and a secondary side assembly arranged on the periphery of the ultrasonic knife handle, and an ultrasonic power supply generator. The ultrasonic knife handle assembly is arranged at the lower end of the high-speed electric spindle, so that the secondary side assembly corresponds to the primary side assembly up and down. The ultrasonic power supply generator is connected with the primary side assembly. According to the rotary ultrasonic machining device based on non-contact energy transfer, the ultrasonic machining technology can be directly combined with existing computer numerical control (CNC) machining centers such as CNC engraving and milling machines, engraving and milling machines, high-gloss CNC machines and drilling and tapping centers, and original spindles do not need to be modified; non-contact energy transfer of ultrasonic waves is achieved through the primary side assembly and the secondary side assembly, and the rotation speed reaches 10,000 turns/min; in addition, the automatic knife switching function can be achieved by using an exiting magazine.