The invention provides a method for modeling a control object in a cooling process of a central air conditioner, relating to the field of cooling control technologies. The method has the advantages that the modeling accuracy and interference resistance are improved. According to the method, a pulse response curve of the control object is obtained firstly in a measurement manner, a step response curve and a ramp response curve are then obtained, a difference equation is written according to a measurement sample, the proportionality constant, time constant and lag time constant of the control object are obtained by using a least square method, a typical second-order plus lag object model is combined so as to obtain a pulse transfer function, and a difference equation of a control object model is further obtained. According to the method provided by the invention, the requirements for experimental conditions and site environments are low, the method has a filter action, the interference resistance is stronger, the modeling accuracy and reliability are high, and the modeling accuracy can be increased to be less than 3% from 7% compared with that of the conventional ascending curve method.