The zero-cross modulation technology is a communication technology for distribution network, different from the traditional distribution network power line carrier communication technology. Its basic principle is to use the TWACS of the power frequency voltage fundamental wave to realize the signal transmission, and the modulation signal frequency is low It can be long-distance communication across the transformer. The data reliability and data through rate are high. It has broad application prospects in real-time communication less demanding situations. This paper first introduces the principle of the zero-cross modulation technology, and then details the generation and the identification of the voltage modulation signal. Practice shows that the transmission success rate of zero-cross modulation signal is up to100%. Meet the actual needs.