Abstract: Aiming at the problem of temperature imbalance and overflow or water shortage caused by water level imbalance in hot and cold water tanks in accelerated durability test of heat meter, an automatic incremental PID control method is proposed for water level balance. The incremental PID algorithm is used to calculate the control increment and control time of the water tank level in the cold and hot shock test, and then the sequential action of the return water valve of the cold and hot water tank is accurately controlled, and the balance control of the water tank level is realized. Combined with MATLAB simulation analysis and comparison of the effect before and after control, the feasibility and reliability of the automatic balancing method is verified, and the response speed is fast and stable, which can realize the purpose of improving the adaptive ability of the water level control system, and then realize the balancing and controlling of the level of hot and cold water tanks.