Abstract: and basic proposition of welfare pluralism. The reform of the supply side of public cultural services and the development of the theory of welfare pluralism give the institutional legitimacy and theoretical rationality to the participation of social organizations in reading promotion. This paper takes the “Three Plus Two Books” reading program as an example, focuses on rural reading promotion in Dayi County, Sichuan Province, and conducts case studies to explore the practical mechanism and strategy selection of social organizations’ participation in rural reading promotion from the perspective of welfare pluralism. In order to meet the needs of the masses and improve the service efficiency, social organizations have gradually developed four mechanisms of reading promotion, such as resource integration, professional services, supply and demand regulation, and institutional guarantee, which effectively “fill in” the deficiencies of the government and the market with their unique advantages. However, in the process of providing high-quality services, there are still many difficulties such as low enthusiasm for participation of the masses, lack of professional personnel, underutilized role of digitalization, and insufficient funding guarantee. Therefore, social organizations should position themselves accurately, formulate development strategies, and fully improve the effectiveness of reading promotion.