[目的/意义]文章旨在厘清旁观者用户对网络违法和不良信息干预意愿的触发机理，以为用户参与网络信息内容生态治理的具体实施路径提供有益参考。[方法/过程]通过扎根理论方法识别触发旁观者用户干预网络违法和不良信息意愿的因素并构建触发机理模型，然后采用ISM-MICMAC方法，明晰触发因素的关联路径与层级关系。[结果/结论]研究发现以下三条触发路径：“利益相关/文化素养/信息素养→风险感知→社会责任感→自我效能→干预意愿”“涉入程度/社会心理距离→社会责任感/社会危害感知→自我效能→干预意愿”和“涉入程度/社会心理距离/信息内容恶劣→触发情绪→干预意愿”。同时，时间充足、举报导航、政策支持、社会支持和平台支持会直接触发旁观者用户干预意愿。

[Purpose/significance] This paper aims to clarify the triggering mechanism of bystander users' willingness to intervene with Internet illegal and undesirable information, so as to provide useful reference for the concrete imple⁃mentation path of users' participation in the ecological governance of network information content. [Method/process]This paper uses the grounded theory to identify the factors that trigger bystander users' intention to intervene with ille⁃gal and undesirable information on the network and constructs a trigger mechanism model. Then, ISM-MICMAC is ad⁃opted to clarify the correlation path and hierarchical relationship of trigger factors. [Result/conclusion] The results show that there are the following three trigger pathways:“stakeholder/ cultural literacy/ information literacy→risk per⁃ception→social responsibility→self-efficiency→intervention intention”“involvement level/ social psychological dis⁃tance→social responsibility/ social hazard perception→self-efficiency→intervention intention”and“involvement lev⁃el/ social psychological distance/ bad information content→trigger emotion→intervention intention”. Meanwhile, suffi⁃cient time, report navigation, policy support, social support and platform support directly trigger bystander users’inter⁃vention intention.