This study explored the user-generated translation activity in the context of the Chinese online social media. It focused on Bilibili content creators dedicated to translating public comments on China-related videos posted on international social media platforms such as YouTube, and creating videos featuring Chinese translated comments. Viewing their translation actions as events in a collective activity system, the authors collected data from 30 participants through a questionnaire and follow-up interviews with two participants who have recently worked on videos about China’s fight against Covid-19. All the data were analysed by using Engeström’s activity theory model to create an activity model showing how their user-generated translation activity was conducted. In this study, we observed that the participants, as the non-professional translation community on the Chinese online social media, were breaking down linguistic borders for fans and viewers, and postulated the possible interaction between the user-generated translation work and their better understanding of how the world saw China through grassroots expression of opinions.