Research questions: This study examined gender difference in the effect of post-learning positive emotion on consolidation of memory for definitions of English vocabulary. Methodology: A 2 (emotion group: neutral and positive) × 2 (gender: male and female) × 2 (emotion duration: 3 and 9 min) design was used. Participants memorized Chinese definitions of English words, took an immediate test, watched a neutral (lasting for 3 or 9 min) or positive (lasting for 3 or 9 min) video, and took a delayed memory test. Data and Analysis: Data of male ( n = 59) and female ( n = 67) participants were analyzed. For evaluation of emotion induction, a 3 (time: before watching, during watching, and after watching) × 2 (emotion group: neutral and positive) × 2 (gender: male and female) × 2 (emotion duration: 3 and 9 min) was respectively conducted on pleasure and arousal ratings. For memory performance, a similar analysis of variance without time as a factor was conducted. Findings: With a 3-min duration, positive emotion had little effect on memory consolidation. However, with a 9-min duration, positive emotion tended to impair memory consolidation for males but not for females. Originality: Extending the literature showing females’ superiority in memory for words and pictures, this study shows that female students also have memory advantage in English vocabulary. Furthermore, this is the first study suggesting that memory consolidation of male students is more likely to be disrupted by a relatively long duration of positive emotion after learning. Significance/implications: The current finding on gender difference may shed new light on employing emotion as a strategy of memory intervention. There seems to be a need to keep males rather than females from post-learning positive emotion, especially when emotion duration is relatively long.