The study aimed to investigate whether or not negotiation of meaning is effective in L2 vocabulary acquisition of Chinese learners of English in the classroom setting. In the study there were two experimental groups (pre-modified input and negotiation of meaning) and two control groups (pre-modified input). The four groups were required to do a pre-vocabulary test, a match task and a post-vocabulary test respectively. The study showed: (1) as far as the high school groups are concerned, the experimental group outperformed the control group in terms of comprehensible input in the match task. The experimental group also did better than the control group in terms of acquiring new words in the post-vocabulary test. A strong correlation is found between comprehensible input, negotiation of meaning and acquiring new words in the high school groups; 2) As regards the college groups, the experimental group also outperformed the control group in terms of acquiring new words in the post-vocabulary test; however, two groups had no difference in obtaining comprehensible input in the match task, and no correlation was found between comprehensible input, negotiation of meaning and acquiring new words.