The invention provides an overheating steam temperature predicting fuzzy self-adaptive PID control method for a thermal power generating unit. The method comprises the steps that controller parameters are initialized; data of overheating steam temperatures of the thermal power generating unit at all moments and temperature reducing water-spraying valve opening degree are acquired; an augmented state space Takagi-Sugeno fuzzy model is established based on process variable data; the augmented state space Takagi-Sugeno fuzzy model is utilized to optimize and solve PID controller parameters; the temperature reducing water-spraying valve opening degree is controlled according to the PID controller parameters at the current moment, and accordingly overheating steam temperature is controlled. A next sampling period begins, the step 4 is repeated, and the process from the step 4 to the step 6 is repeatedly performed. The method integrates the advantages of fuzzy control, prediction control and PID control, namely, a prediction function of prediction control, a nonlinear-system excellent control effect of fuzzy control, and convenient realization of PID control, the control quality is high, the form is simple, and the method is easy to achieve, economical and safe.