The invention relates to the technical field of acoustic metering and particularly discloses a generating device and method for the random sound-pressure phase difference of a microphone. In the generating device, a plurality of reference microphones are fixedly installed at one ends of a plurality of active coupling cavities in a way of one-to-one correspondence, the reference microphones are connected with a data collection card by a signal amplifier A, the data collection card is connected with a computer, and the signals of the active coupling cavities, which are detected by the reference microphones, are collected by the data collection card and are input into the computer after the signals are amplified by the signal amplifier A; and the computer is connected with the active coupling cavities by a multi-channel signal source and is used for controlling the signals input to the active coupling cavities by the multi-channel signal source. According to the generating device and the method, the synchronous control of the sound fields of a multi-channel microphone can be realized, random sound-pressure phase difference between every two channels is generated, and analog sound sources with various modes can be provided for calibrating a multi-channel acoustic testing system. According to the generating device and the method for the random sound-pressure phase difference of the microphone, the sound-pressure level control accuracy reaches 0.1dB, and the phase-difference control accuracy can reach 0.1 degree.