To date, most studies have focused on IVA through reading, speaking and listening, with few research on the function of translation tasks. This study investigates the effectiveness of different translation tasks on college student L2 IVA and retention. 60 Chinese College students taking English as L2, were divided into 2 parallel groups, finished different translation tasks (L1-L2 and L2-L1) respectively, and then underwent immediate and delayed vocabulary post-tests. The results showed that (1) both translation tasks facilitate learners’ L2 IVA with L1-L2 translation task performing better; (2) L1-L2 translation task generates a higher level of productive vocabulary knowledge; (3) the IVA of both tasks decrease dramatically over time, and the advantage of L1-L2 in promoting higher level of vocabulary knowledge gradually vanishes. The findings enrich the scope of IVA study, verify the value of translation exercise on L2 IVA and provide useful and practical implications for IVA teaching and learning.