If the intelligent building's indoor environment's constant temperature is accurately controlled, the comfort of the building can be improved. When we perform constant temperature control, there will be large fluctuations in the supply air temperature, which results in the traditional methods that cannot control the temperature within a reasonable range. Therefore, the paper proposes an optimal control method for the indoor environment constant temperature of intelligent buildings. In the IoT environment, we integrate the multi-agent technology to design the temperature fuzzy control structure, determine the input and output variables of the intelligent building temperature control system and its fuzzy set, use the dynamic analysis method to modify the fuzzy rules, and integrate it with bilinear The control algorithm builds a dynamic temperature control model for intelligent buildings to maintain the indoor temperature at the set value when the supply air temperature fluctuates significantly. This method makes up for the shortcomings that the current system cannot adapt to the intelligent building environment changes. The simulation results show that compared with the traditional algorithm, the improved algorithm can significantly improve the robustness of the intelligent building constant temperature control, and the temperature control stability is vital.