Abstract: A rotary body dynamic balance detection and correction device, comprising a detection assembly and a machining correction assembly. The detection assembly is configured to detect the amount of unbalance of a rotary body. The machining correction assembly is configured to machine an outer peripheral face of the rotary body to form a correction hole, so that the value of the amount of unbalance of the machined rotary body does not exceed the value of a preset maximum amount of unbalance. The rotary body dynamic balance detection and correction device can effectively correct the amount of unbalance of the rotary body, reduce the degree of unbalance of the rotary body, and avoid excessive lateral vibration generated when the rotary body rotates at a high speed. A rotary body dynamic balance detection and correction method and a numerical control tool holder are also provided.