Abstract: Focusing on the specific characteristics of the audio equipment used by field troop, this paper does the related research and experiments about power amplifier and loudspeaker in order to satisfy the system's requirements in small volume, light weight and long distance sound transmission with high sound pressure. This paper firstly compares and analyzes the advantages and disadvantages of the exiting power amplifiers in principle, then measures the parameters with the AP2722 Audio test instrument (AP means Audio Precision), and do the further test under rigorous conditions. After comparative analysis of different schemes, to meet the requirement of long distance audio signal transmission with high sound pressure, the way to improve sensitivity of single loudspeaker is selected, which includes improving the magnetic circuit of the single loudspeaker, appropriately choosing materials of diaphragm, voice coil, voice coil line, frame etc, and improving the design of unit structure. Then the LMS, which is an audio test system from America Linearx System Company, is taken as the test tool and used for normal temperature aging and environmental test to improve the system's parameters, and finally to get the required sensitivity and reliability for the audio loudspeaker. The subjective and objective test as well as the listening and evaluation test show that the audio system can meet the design requirements.