Abstract: Exploration vessel positioning provides a reference position for locating underwater targets in marine seismic exploration. China is highly dependent on overseas commercial services, which are expensive in equipment costs and service fees, to accomplish exploration vessel positioning at present. This paper evaluates the service performance of the Beidou PPP-B2b signal, for free real-time precise point positioning provided by China's BDS-3 system for Asian-Pacific users, in the navigation and positioning of offshore exploration vessels. The experimental results show that in land static tests, the plane and elevation positioning accuracies are 7.2 and 12.1 cm, respectively, for the Beidou-only system and increase to 4.8 and 11.1 cm, respectively, for the Beidou+GPS system; in the open-sea dynamic tests, the average deviations of real-time positioning in the E, N, and U directions are 6.6, 2.3, and 14.6 cm, respectively, comparable to commercial positioning services. This study demonstrates the significant application potential of the Beidou PPP-B2b signal in marine seismic exploration, offering a cost-effective solution that reduces dependence on overseas services.