A shunt regulator for solar cell arrays, including a power MOS tube M1 for splitting solar cell arrays, a power MOS tube M2 for charging batteries with solar cell arrays, and a main error amplifier for adjusting bus voltage , the battery error amplifier used to regulate the battery charging current. The output of the main error amplifier enters the logic control after passing through the hysteresis comparator to generate shunt drive pulses to control the opening and closing of the power MOS transistor M1, so as to control the constant bus voltage. The output of the battery error amplifier enters the logic control after passing through the hysteresis comparator, generates driving pulses and passes through the drive control unit to control the opening and closing of the power MOS transistor M2, so as to control the size of the battery charging current. The invention adopts the power MOS tube M2 to replace the traditional charging regulator, which saves the volume and weight of the power controller, and is not only suitable for low-orbit spacecraft requiring frequent charging, but also for high-orbit regular charging spacecraft.