The purpose of this paper is to investigate if customer participation has the double-edged sword problem and how it impacts the co-creation intention of brand value under social media. To explore the relationship, we construct a research model from the perspective of value co-creation and cognitive behaviour theory in the context of social media. 385 valid samples were collected through a field questionnaire, and the structural equation model was used to test the research hypotheses. The results indicate that customer participation through social media has a double-edged sword effect, enhancing the perceived prosocial influence, but also causing social media fatigue. Perceived prosocial influence and social media fatigue play a dual mediating effect on the relationship between customer participation and co-creation intention of brand value. Moreover, brand attachment moderates the relationship between perceived prosocial influence and co-creation intention of brand value. Majority of the studies have found that customer participation has positive effect, but a few studies have found that customer participation has a certain “dark side”. This study focuses on the double-edged sword problem of customer participation through social media, as well as its effect on co-creation intention of brand value, thus contribution to the value co-creation theory. This research also analyses the positive effect of perceived prosocial influence and the negative effects of social media fatigue, thus supporting effective social media participation strategies for companies.