In the production of electronic products such as integrated circuit boards, the reflow furnace automatically solders electronic components to the circuit board by heating. Therefore, maintaining the temperature required by the process for all parts of the reflow furnace is very important to the quality of the product.This article mainly optimizes the furnace temperature curve of the reflow furnace. We have established a furnace temperature model based on the ordinary differential equations of heat convection and heat radiation and Newton’s law of cooling. After calculation, the midpoint end of small temperature zone 3, 6, and 7 and the welding zone center temperature of small temperature zone 8 are 139.8444°C, 168.1605°C, 190.0927°C and 225.6867°C, respectively.On the basis of the previous model, we have introduced the requirement of symmetry on both sides of the highest temperature for the part of the furnace temperature curve that exceeds 217°C. We have established a single-objective optimization model, with symmetry index as the optimization goal. The smaller the index, the more symmetrical the shape is. Using dichotomy and linear search algorithm to solve the model, the optimal furnace passing speed is 83cm/min. The setting values of each temperature zone are 185°C, 167°C, 186°C, 225°C, 265°C, and the minimum non-overlap rate is 13.8%.