Abstract: The raw wastewater with suitable and stable temperature was required for the verification and assessment on the biological treatment technologies of water pollution control. Aiming at the uncertainty, non-linearity and big lag characteristics of the temperature control system, the algorithm of self-adjustment fuzzy control was adopted. The raw water temperature error and error change ratio before and after the heat exchanger were acted as input. According to the raw water temperature feedback after the heat exchanger, the online self-adjusting was performed for output of controller, and the hot water valve was in real-time control to adjust the hot water flow, so that the raw water after the heat exchanger quickly reached the set temperature and held stable, providing necessary conditions for realizing objective verification and assessment on the biological treatment technologies. The results of Simulink simulation experiment based on Matlab working conditions showed that the fuzzy self-adjustment controller had good dynamic properties, and temperature control system of the controller obtained good quickness, stability and strong robustness.