This study investigates lexical complexity in spoken Korean produced by Chinese students learning Korean by measuring lexical density and diversity. This study intends to examine the developmental differences in lexical complexity according to different groups and tasks. 136 Chinese students have been divided into three groups: basic group, intermediate group and advanced group. The results of this study reveal that the lexical diversity of the three groups shows a statistical significance, while the lexical density of the three groups does not show a statistical significance. Lexical diversity is statistically significant among the three groups in all tasks. However, lexical density was statistically significant among the three groups in some tasks. Also, the lexical diversity of the divergent tasks was higher than the convergent tasks. The result of this study would not only provide the validity of measurement tools of lexical complexity in spoken Korean, but also present basic information of measuring learners’ spoken production. (UNSW & Yonsei University)