A capacitive full-wave circuit for LED light strings makes use of capacitors and diodes together to drive a LED string with full AC waves. Different from the conventional four-diode full-wave rectifying circuit, one embodiment of capacitive full-wave circuit includes two capacitors and two diodes. Because of the large imaginary impedance, the capacitors not only limit and the voltage and current through the LEDs, but also consume almost no electrical power. The electrical current-voltage performance can be further improved by introducing four resistors with a cost of some additional power consumption. A LED light string module with the capacitive full-wave circuit is also presented, with the capacitive full-wave circuit integrated inside of a front power plug and a back power socket.