There is evidence that emotion induced in the process of encoding impairs associative memory, yet the effect of post-encoding emotion on second language vocabulary learning remains largely unclear. An experiment was carried out to examine the effects of post-encoding emotion (positive, negative, and neutral) on learning of multidimensional vocabulary knowledge, that is, productive and receptive vocabulary knowledge in five aspects: orthography, meaning and form, grammatical function, syntagmatic association, and paradigmatic association. To carry out the study, 106 Chinese students voluntarily took part in the present study and they were randomly divided into positive group, negative group, and control group. After completing the vocabulary learning task and undergoing emotion manipulation by three video clips (positive, negative, and neutral), all participants sequentially took a multidimensional vocabulary test containing 10 subtests in a immediate, delayed, and post-delayed tests. The result showed a significant impairing effect of post-encoding emotion, especially positive one, on both item memory and associative memory under a longer retention interval, and no significant effect of post-encoding emotion upon semantic memory was found. Both theoretical and practical implications for second language vocabulary learning was put forward.