It is widely accepted that mastery of vocabulary is an essential component of second language acquisition and one can not learn a language without vocabulary. However, in China the teaching and learning of English vocabulary does not lead to the expected results, and both teachers and learners feel discouraged. More and more teachers and educators have realized that for vocabulary learning it is far from enough to completely rely on teachers’ instructions in class, and students also should share their responsibilities. However, when it comes to foreign language vocabulary learning, there aren’t many observational and experimental studies on vocabulary autonomous learning, and therefore, it is evident that investigations are necessary for an understanding of issues regarding vocabulary autonomous learning. So the author, by means of questionnaire, has conducted a survey followed by an analysis on learner autonomy in vocabulary building among college students.The study aims to investigate:1. The current situation of learner autonomy in vocabulary learning among university students;2. The relationship between students’ achievements and their practice in vocabulary autonomous learning;3. Difference in autonomous learning between good learners and poor learners.The study has demonstrated that although most of the students demonstrate very limited learner autonomy in vocabulary learning, the correlation study between vocabulary autonomous learning and CET4 scores and the t-test between more successful learners and less successful learners indicate that there are some striking features of more successful learners and less successful learners in vocabulary autonomous learning. This study reflects, to a certain degree, the current situation in vocabulary autonomous learning among college students, and some pedagogical suggestions are also made for further study on both teacher’s side and learner’s side.