Hashtag activity,as a large-scale symbolic practice in social media space with claim-direction,plays an important role in online public events.The generative mechanisms of 37 hashtag activities that took place between 2017-2023 were explored through a qualitative comparative analysis.The analysis shows that,firstly,media support and the nature of the event constituted the sufficient conditions for the generative diffusion of hashtag activities in public events,which helped to promote the fulfillment of the hashtag activities'claims.Secondly,the remaining conditional variables act on the generation mechanism of labeling discourse actions through three paths,namely,a mutual aid and rescue mechanism,a media-led mechanism,and a resistance mobilization mechanism.Thirdly,the three conditional variables of media support,narrative mode and discourse frame show obvious time effects in a continuous time scale.This paper tries to put forward the concept of"activity-oriented discourse space"to describe the turning process of Chinese netizens'conception of events.