Based on system justification theory, this study explored the mechanism through which bystanders’ observed of coworkers’ deviant helping behavior influences moral voice, utilizing data gathered from multi-wave questionnaire surveys (Study 1, 325 participants) and a situational experiment (Study 2, 218 participants), and the empirical results indicated that moral outrage and moral justification play a dual-mediating role between observing coworker deviant helping behavior and moral voice, i.e., observing coworker deviant helping behavior suppress moral outrage and reduces moral voice. Observing coworker deviant helping behavior increase moral justification and decreases moral voice. In addition, the renqing-oriented organizational climate perceptions plays a positive moderating role in the above relationships.