Prospective memory (PM) refers to remembering to perform a planned action at a future time. Implementation intention is an encoding method in the form of “if situation Y is encountered, then will initiate the goal-directed behavior X”. It has been applied to improve PM performances. The present study conducted a systematic and meta-analytic review on the effect and mechanism of implementation intention on PM. In the meta-analysis, 36 comparisons were included. The results showed that for healthy young adults, the overall effect of implementation intention in improving PM performances was signi cant with a medium effect size (d=0.445). The combined verbal and imagery form of implemen-tation intention had a relatively larger effect size (d=0.590). For older adults, implementation intention had a medium to large effect size on their PM performances (d=0.680). As for the mechanism, implementation intention seemed to reduce ongoing task performances in young adults as re ected by longer reaction time (d=0.224) though the effect size was small. The present study supports the positive effect of implementation intention on PM. The mechanism and potential implications of this promising strategy especially for clinical/sub-clinical people are discussed.