The utility model relates to a portable audio and video transmission device and a monitoring system. The technical scheme electrically connects a remote monitor with a wireless receiver and electrically connects an audio and video collector and a wireless transmitter so that the remote monitor and the portable audio and video transmission device are capable of carrying out wireless communication and thus audio and video information acquired by the audio and video collector is transmitted conveniently and rapidly in a remote and real-time manner through a wireless network and the field condition can be mastered clearly and timely by related personnel. At the same time, because circuit boards in the portable audio and video transmission device are disassembled into a first circuit board, a second circuit board and a third circuit board according to difference of functions, and all the circuit boards are arranged in the portable audio and video transmission device respectively independently so that the volume of the portable audio and video transmission device is reduced and the device is convenient to carry.