A free-space optical (FSO) communication system with video and audio signals synchronous wireless transmission has been designed and demonstrated.The system consists of signal transmitter,modulator and receiver.The video and audio signals outputted from signal transmitter were transformed into multiplexer signal by means of the time-division multiplexer (TDM).The multiplexer signal was added to laser beam when it connected to the acoustic-optical modulator (AOM) in the form of electric signal.The receiver was used to convert the light signal outputted from AOM into electric signal.The 3 dB bandwidth of the system is 6.7 MHz.Through the process of electric-light-electric conversion,the synchronous wireless transmission of video and audio signals was achieved with the combination of time-division multiplexing and acousto-optic modulation.The circuit of time-division multiplexer/de-multiplexer and photoelectric conversion circuit were built according to the specific work environment.The quality of the output signal was controlled and adjusted by a microcontroller.The experiments proves that the system has some advantages of flexibility,practicality and low cost.And it provides an efficient scheme of synchronous wireless transmission of video and audio signals for monitoring system and TV access network.