The traditional power line carrier equipment often makes use of digital single channel Weaver modulation to implement single-side-band（SSB） modulation. The audio effectively transmitted frequency band of the power line carrier equipment is 300 Hz～3 840 Hz with 4 kHz nominal bandwidth， that is， the effectively transmitted bandwidth equals 3 540 Hz. To increase the effectively transmitted bandwidth， digital multiplex channel Weaver complex modulation is employed to implement SSB modulation. An account is given of the principles and implementation of the digital multiplex channel Weaver complex modulation， and a discussion made on the differences between the modulation and the traditional power line carrier equipment.