In the context of social governance, as important government partners, social organizations are important forces involved in rural construction. However, the newly involved social organizations need to obtain legal approval to embed local power and social structure and exert their influence effectively. From the perspective of legitimacy, a detailed examination of typical cases of social organizations participating in rural social governance reveals that the main legitimacy challenges that social organizations face in participating in rural social governance are regulatory legitimacy, cognitive legitimacy, and legal legitimacy, and the acquisition of cognitive legitimacy is the most important and the most difficult. Social organizations need to adopt adaptive strategies, selective strategies, and manipulative strategies to obtain legal identity. In the future, legal legitimacy will still face institutional and capacity challenges. Therefore, the government must give more support to the legitimacy of social organizations from the perspective of subjective value recognition, and social organizations must organically combine legitimacy acquisition strategies and governance action strategies to reshape the path of action. 