Abstract: The establishment of nature reserves can be the most effective measure to conserve biodiversity and the construction of a nature reserve system with national parks as the main body has been a major initiative to promote the construction of ecological civilization in China. Acoustic monitoring has been a new method to estimate biodiversity by recording the types and changes of species’ sounds in the natural environment, and its application in biodiversity monitoring in nature reserves has become more and more widespread. In this paper, the advantages and disadvantages of acoustic monitoring in the biodiversity conservation of nature reserves, its application, and the key points of monitoring implementation were sorted out. Acoustic monitoring realized passive collection, which allowed for continuous, complete, and relatively low-cost data, increasing the possibility of monitoring at larger species scales. It can help to facilitate the establishment of species list inventories, the assessment of monitored taxa populations, and the observation of dynamics, while animal sounds can be used to determine their physiological status and habitat quality. However, there was still a lack of standardized and resource-sharing acoustic databases, few long-term monitoring programs, inconsistent data from equipment differences, and controversy over the fidelity and accuracy of index-based biodiversity assessment. In the future, the need to further improve the ability of acoustics for biodiversity prediction through a large number of scientific studies will still be needed. Based on this, several recommendations for the use of acoustics as a monitoring tool in China’s nature reserves were proposed to promote the monitoring and conservation of biodiversity in the nature reserve system.