NOVELTY - An operation technique of methanol rectifying system is improved by reducing rectifying feeding quantity, increasing backflow quantity of a pressurizing tower, closing recovery of the pressurizing tower, putting liquid level of the pressurizing tower and liquid level of a backflow groove of the pressurizing tower in normal operation, increasing recovery of a normal-pressure tower, sending a fine methanol cooler of the pressurizing tower for overhauling, and using the cooler.    USE - Method for improving operation technique of methanol rectifying system (claimed).    ADVANTAGE - The method ensures normal rectifying operation by the mode, realizes normal product recovery during rectifying progress, and saves time and human resource without influence on quality of product.    DETAILED DESCRIPTION - Improving an operation technique of methanol rectifying system involves reducing rectifying feeding quantity from 69 m3/hour to 36 m3/hour, increasing backflow quantity of a pressurizing tower from 63 m3/hour to 90 m3/hour according to pressure and temperature of each point of a rectifying tower, and liquid level change conditions of three towers and a backflow groove to ensure normal and steady operation of the three towers. Under precondition that the pressurizing tower operates steadily, recovery quantity of the pressurizing tower is reduced from 32 m3/hour to 0 m3/hour until all recovery valves of the pressurizing tower are closed and the pressurizing tower is in full-backflow state. The remaining liquid level of the pressurizing tower is 65-71% and liquid level of a backflow groove of the pressurizing tower is 28-34% that is state of normal operation before quantity reduction. A normal-pressure tower is in balanced operation state to recover product after full backflow of the pressurizing tower. Rectifying feeding quantity is added and subtracted to ensure liquid level of the pressurizing tower to 65-71% and liquid level of the backflow groove of the pressurizing tower to 28-34%. After technique is finished, a fine methanol cooler of the pressurizing tower stops working and is sent for overhauling. The fine methanol cooler is put in use and feeding quantity can be increased at a speed of 1-2 m3/hour to 36-50 m3/hour until the rectifying recovers a normal feeding quantity of 69 m3/hour. When liquid level of the backflow groove of the pressurizing tower increases, recovery of the pressurizing tower is automatic and begins to recover product to resume the rectifying to normal operation state.