A control method for a hydraulic control turning system of a generator rotor includes: establishing a length relationship table between multiple hydraulic cylinders of the hydraulic control turning system; selecting a reference hydraulic cylinder; acquiring current lengths of the multiple hydraulic cylinders when the multiple hydraulic cylinders are located at error correction positions, specifically, the error correction positions are positions where the hydraulic cylinders are located after completing at least one driving stroke; and adjusting lengths of the other hydraulic cylinders corresponding to a next driving stroke to conform with the length relationship table, with the current length of the reference hydraulic cylinder as a determining reference. With such an arrangement, the accumulated dimension error between the hydraulic cylinders may be dynamically corrected during the turning operation, thereby ensuring that the turning pins are accurately aligned with the pin holes in the generator, and the corresponding turning operation is performed after the generator set is locked, thereby greatly improving the operation accuracy and operation reliability of the turning system. Based on this, a control device for a hydraulic control turning system of a generator rotor is further provided according to the present application.