Objective: To explore the effects of task relevance of facial expressions on individual’s workingmemory(WM) updating. Methods: Participants performed a 1-back and a 2-back task with facialexpressions as task relevant or irrelevant stimuli. Results: When facial expressions were task-relevantstimuli, participants made less errors when encoding happy and sad schematic faces than neutral faces.When facial expressions were task-irrelevant stimuli, participants made less errors when encodinghappy and sad schematic faces than neutral faces and showed fastest updating response times whenencoding happy faces in 1-back condition. Participants made more errors and showed faster updatingresponse time when encoding happy faces than sad and neutral faces in 2-back condition. There wereno difference in updating response times and accuracy when encoding sad and neutral faces in 2-backcondition. Conclusion: When facial expressions were task-relevant stimuli, emotional valence enhancedindividual’s WM updating. When facial expressions were task-irrelevant stimuli, task difficulty moderatedthe effects of emotional valence on individual’s WM updating. Emotional valence enhanced individual’sWM updating in the easier task(1-back).However, only schematic happy faces impaired individual’s WMupdating in the more difficult task(2-back).