Abstract: The dynamic balance detecting device includes a platform, a pillar, a main shaft, a vibration sensor, a rotation sensor, a dynamic measuring tester, and a controller. The pillar is connected to the platform. The main shaft is positioned on the pillar for driving a rotor. The vibration sensor is positioned adjacent to the main shaft for detecting vibration amount of the main shaft. The rotation sensor is positioned adjacent to the main shaft and spaced from the vibration sensor for detecting a rotation of the main shaft. The dynamic measuring tester is positioned on the platform for receiving vibration data obtained by the vibration sensor and rotation data obtained by the rotation sensor in real time to analyze and determine whether dynamic balance of the rotor achieving as required, and calculates a dynamic balance regulating amount for the rotor.