The invention relates to a crane accumulative error elimination system and a crane accumulative error elimination method. The crane accumulative error elimination system comprises a PLC automatic control system, an emergency manual system, a luffing system for driving a luffing winch, a main lifting system, an auxiliary main lifting system, a rotation system, a main motor, a main pump and a hydraulic oil tank, wherein the PLC automatic control system controls a hydraulic control proportional multi-way valve through an electric proportional pressure reducing valve group, the emergency manual system comprises an emergency pump group connected to the hydraulic oil tank, and a hydraulic handle, the emergency pump group controls the luffing system, the main lifting system, the auxiliary main lifting system and the rotation system through the hydraulic handle, an electronic control handle controls the electric proportional pressure reducing valve group through the PLC automatic control system, and the PLC automatic control system detects the rotation speeds of a main lifting winch, an auxiliary main lifting winch, a luffing winch and a rotation mechanism respectively through an encoder.