Progress of process control technology has motivated extensive research on various aspects of control for air-conditioning refrigeration systems. In refrigeration station systems, the steady-state operation of the chiller should take into account the roles of temperature, fluid flow, and heat transfer. These are restricted by the following parameters, i.e., (i) demand of refrigeration load, (ii) inlet temperature of condenser, (iii) structure features of the chillers, and (iv) impact of outdoor meteorological parameters. At present, the PID algorithm is widely used to control the operation of water pump in the refrigeration station system. However, PID algorithm may cause oscillation in the case of load changes. Instead, iterative feedback tuning (IFT) method is a model-free method driven by I/O data of the systems. It can adjust the control parameters of the chilled-water pump without destroyed the stable operation of pumps. This thesis is devoted to the development of a fundamental modeling and optimization methodology for the chiller optimal operation of air-conditioning refrigeration-station systems, meanwhile TRNSYS is used for establishing the system model. Based on IFT method, an optimal control system, for the control of constant-temperature-difference between chilled supply and return water, was developed. The iterative feedback controller calculates the optimal control signal of pumps with secant algorithm, and transmits the optimized parameters to the controlled equipment. Therefore, the temperature difference of chilled-water supply and return can maintain at the setpoint of 5 ºC and minimize the tracking error to the least. Simulation results show that, compared with PID algorithm, IFT method achieves better performance.