Reactive power optimization with time-varying load demand in distribution systems is investigated in this paper. The objective of this paper is to determine the proper setting values of capacitor banks and transformer taps for the 24 h in the next day. A heuristic and algorithmic combined approach is proposed in this paper. The approach simplifies the mathematical model of the daily setting values of reactive power/voltage control devices, solves the temporal optimization of each control device by heuristic rules, and then converts the optimization model with time-varying load into the same one as conventional optimization model with constant load. Therefore, the algorithms applied to the conventional optimization model can be easily used to solve the optimization model with time-varying load demand. Results from numerical examples show that a proper dispatch schedule for capacitor banks and transformer taps can be reached by this approach efficiently.