Abstract: As a branch of acoustics, conservation acoustics originated from the need to protect species and their ecological environment. It focusses on theory, technology, and application of acoustics related to conservation, and incorporates with related disciplines such as conservation biology, bioacoustics, and ecoacoustics. The study on bioacoustics of small cetaceans and soundscape of their habitats is helpful to understand the survival status of the population, formulate and implement acoustic-based conservation countermeasures, and promote the conservation of species and ecological environment. The conservation acoustics of small cetaceans in China originated in the 1980s to conserve the baiji (Lipotes vexillifer). In the late 1990s and mid to late 2000s, it gradually transferred to the Yangtze finless porpoise (Neophocena asiaeorientalis a.) and the Indo-Pacific humpback dolphin (Sousa chinensis) from the baiji. In the past 10 years, it has gradually covered several species of small cetaceans distributed in the South China Sea, the Yellow and Bohai Seas. Chinese research in conservation acoustics of small cetaceans has occupied a more prominent position in the international academic community. Over the past 40 years, with the development of acoustical technology and instruments, as well as the urgent need for small cetacean conservation in river and sea, conservation acoustics has transferred from individuals in captivity to wild groups, the recording method of acoustic signals has updated from a single hydrophone to a fully automatic hydrophone array, and the research content has expanded from acoustical signals and auditory characteristics to wide-range and long-term passive acoustic monitoring, as well as underwater soundscape and underwater noise impact and mitigation. Basic research and technology development of conservation acoustics have provided support for small cetacean conservation. In the coming more than ten years, China's small cetacean conservation acoustics will be expected to make more quick progress in basic theory, technology research and development, as well as conservation applications, with the development and integration of big data science, artificial intelligence technology and acoustics.