Abstract: Underwater target detection faces severe challenges due to the enhanced acoustic stealth capabilities of targets and the anomalous sound propagation phenomena within complex ocean waveguides. Passive sonar, which relies on the self-radiated noise of targets, offers concealment but suffers from a sharp decrease in detection range when targeting “quiet” objects. Active sonar, which detects targets by emitting sound waves, has a larger detection range; however, it is limited by reverberation interference, detection blind spots, and at risk of exposure. This paper discusses the development of key technologies for active and passive sonar detection, highlighting existing issues in light of advances in submarine stealth technology. It proposes an active-passive joint detection system that combines active multi-base detection with distributed passive receiving networks. Additionally, a “daily alert-critical detection” strategy for active and passive joint detection is introduced, and the collaborative architecture and implementation methods are explored. The paper aims to provide theoretical and technical reference for the multimodal collaborative design of underwater detection systems, and to promote the evolution of underwater acoustic detection technologies toward higher efficiency, intelligence and sustainability.