The invention relates to the technical field of cold rolling, in particular to an optimization method and system for process parameters of a withdrawal and straightening machine. The method comprises: setting parameters of a finite element basic calculation model of the withdrawal and straightening machine according to a first array corresponding to a layer on which pre-withdrawn-and-straightened strip steel is located, inputting at least four second arrays, and storing a calculated torque load into a corresponding second array; calculating a multi-variable regression function with a mathematic regression method, wherein variables of the multi-variable regression function are a first parameter, a second parameter, an elongation rate and a torque load; and presetting the values of a target torque load and a target elongation rate, calculating a relational function of the first parameter and the second parameter, and optimizing the process parameters of the withdrawal and straightening machine. The system comprises a strip steel classification unit, a parameter setting unit, a data generation unit, a first calculation unit, a second calculation unit and a parameter optimization unit. According to the optimization method and system for the process parameters of the withdrawal and straightening machine, provided by the invention, a load of the withdrawal and straightening machine can be controlled to be within a target value, so that a withdrawal and straightening program can be executed stably and reliably.