To realize the optimal reactive power regulation of power systems， a new Tabu search based approach is proposed. The solution is composed of the beginning time and the control variables of each time-interval， which can avoid the problem of optimizing the time-intervals and the reactive power of each time-interval separately so that the overall optimality is guaranteed. In the cases of the neighborhood solutions falling into infeasible area， i.e.， the voltage constraints are not satisfied， the index is switched to the voltage quality， so as to guarantee the searching process can work and gradually reach the feasible area. Once neighborhood solutions return to a feasible area， the index is switched back to losses reduction during the whole day. IEEE 6-bus system， IEEE 14-bus system and IEEE 30-bus system are used as the test examples. The results show that the approaches proposed are feasible and the introduced improvements are necessary and effective.