Abstract: Citizen science (CS) generates much information over wide geographical areas and extended time scales. CS has grown increasingly important in biodiversity monitoring and sustainable change research, where it is critical in assessing global biodiversity indicators and achieving the United Nations′ sustainable development goals. This study systematically collected photographic information submitted to BirdNET (http://www.birdnet.cn) concerning birds spotted in Chinese provinces. The goals were to (1) determine the number and diversity of birds recorded by the public in each province, (2) comprehend the scope of public contributions, (3) forecast future trends in public contributions, and (4) understand the limiting factors that affect public participation. The number of species and public contributions were collated by province. Cumulative curves and multiple linear regression were used to analyze participation, contributions, future trends, and relevant factors. There were 1 310 species of birds identified using geographical information. At the provincial level, Yunnan Province had the most diverse species (813), and the Ningxia Hui Autonomous Region had the fewest (65). Geographically, the highest number of species was observed in the southwest, with an average of 493 species per province. The lowest number was observed in the northwest, averaging 300 per province. Applying the 80/20 law, the 20% high-ranking bird watchers provided much more photographs, locations, and species contributions than the other 80% (for example, contributing 68.98% of all photographs). The cumulative curve of species observations neared the asymptote after 2018, indicating that the record is close to saturation (the vast majority of Chinese birds have been recorded). The number of bird watchers will continue to increase as more individuals participate and the number of locations increases. The contributions of bird watchers are significantly and positively correlated with the latitude, GDP, forest coverage, and bird species diversity of the provinces. The local species diversity is the main factor attracting bird watchers. Despite the late start and low level of participation in bird-watching activities in China, the number of participants continues to rise, providing increasing amounts of data for ornithological studies that will play an important role in understanding bird species composition and population distribution in China.