[目的/意义]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制，为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]采用情境实验法，将经典旁观者干预模型引入网络违法和不良信息场景，构建旁观者干预意愿形成路径，并进一步引入保护动机理论和信息内容生态素养来探讨该路径的边界条件。[结果/结论]“情感性注意→社会危害感知→网络责任感→自我效能”的旁观者干预意愿触发链条在三类网络违法和不良信息场景中均适用。同时，威胁评估在旁观者干预情境中扮演了“风险激励”的悖论角色，普遍强化了自我效能对干预意愿的影响；结果预期在网络暴力信息和不良意识形态信息情境中显著负向调节了自我效能对干预意愿的影响；信息内容生态素养仅在不良意识形态信息情境下显著负向调节了自我效能对干预意愿的影响。

[Purpose/significance] This study aims to clarify the triggering mechanism of bystander users' willingness to intervene with Internet illegal and malicious information, so as to provide beneficial reference for the concrete imple⁃mentation path of online information content ecological governance. [Method/process] This study employs the experi⁃mental vignette methodology, introducing the classic bystander intervention model into the context of online illegal and harmful information. It constructs a formation path of bystanders' intervention intention, and further incorporates the protection motivation theory and information content ecological literacy to explore the boundary conditions of this path.[Result/conclusion] The "affective attention → social hazard perception → sense of online responsibility → self-effi⁃cacy" path of bystander intervention intention is applicable in three kinds online illegal and harmful information scenar⁃ios. At the same time, threat appraisal plays a paradoxical "risk incentive" role in bystander intervention contexts, gen⁃erally strengthening the influence of self-efficacy on intervention intention. Outcome expectancy significantly and nega⁃tively moderates the relationship between self-efficacy and intervention intention in the contexts of cyberbullying infor⁃mation and malicious ideological information. Moreover, information content ecological literacy significantly and nega⁃tively moderates the relationship between self-efficacy and intervention intention only in the context of malicious ideo⁃logical information.