The utility model discloses a synchronous deviation rectification device of a hoist, relating to the technical field of hoists. A curved pipe is respectively communicated to two sides of a sealed mercury tank symmetrically, wherein the upper end of each curved pipe is communicated with atmosphere; and a liquid-level sensor is respectively arranged in each curved pipe. According to the synchronous deviation rectification device disclosed by the utility model, the mercury tank is sufficiently filled with an appropriate amount of mercury, the center of the mercury tank is fixedly connected with the center of a double-suspension-point valve provided with a hydraulic hoist, and the signal output end of each liquid-level sensor is respectively connected to an oil-control working circuit of each of two hydraulic cylinders. The synchronous deviation rectification device realizes synchronization by controlling the two hydraulic cylinders to work through a mercury balancer and the liquid-level sensors, and ensures that a large-size valve can be opened and closed stably and smoothly, the two hydraulic cylinders have high synchronization precision and the hydraulic hoist has low manufacturing cost.