Due to its varying time delay and parameters, brazing temperature control is the main difficulty in brazing operations. In order to optimize the brazing temperature, the brazing temperature model must first be established. Parameter identification and optimization are effective ways to obtain the precise temperature model of the brazing furnace. In this investigation, the online parameter identification on first order delay temperature model was proposed. Through identifying and calculating for the first order delay temperature model, the mode parameters and delay time were obtained. Next, PID parameters optimization for the traditional objective function was implemented using a genetic algorithm. The overshoot, static error index and rising time in the third stage of the heating requirements can then be controlled well, with the help of the modified objective function.