Abstract: Aiming at the optimization of the furnace temperature curve when the reflow oven heats circuit boards, the heat transfer model and the optimization search model are established based on Newton’s law of cooling and law of heat conduction. First dividing the entire heating process into three areas. In the separated heating zone, the given experimental data and the least square method are applied to find the time parameters. In the gap zone, first using the heat conduction equation to obtain the pattern of temperature distribution in the gap area, and then obtaining the time constant. In the cooling zone, a polynomial fitting method is used to compute equations. Then, for different process limits, the corresponding optimization goals are established. The Monte Carlo simulation method and the variable step size algorithm are used to accelerate the search process, and the optimal furnace temperature curve under the corresponding conditions is obtained.