This paper presents a gravitational search algorithm (GSA) method for voltage control, which reduces transmission losses by adjusting the reactive power variables, such as generator voltages and other sources of reactive power, such as capacitor banks, and provides better system voltage profile. The objective function of the proposed method is to minimize active power losses in transmission line. GSA method uses new meta-heuristics optimizations which are motivated by Newton's law of gravity and motion. This method is implemented in 500 kV Java-Bali electrical power system. The load flow results showed that after the optimization using GSA method, the active power losses was 244.390 MW, while other optimization methods gave 267.559 MW (GA method) and 245.003 MW (PSO method). Comparing the losses obtained by the three optimization methods, GSA method is better for minimizing the active power losses in transmission line.