The study investigates how developmental stages of EFL learners are related to the representational structure of bilingual lexicons. It was hypothesized that the less advanced L2 learners will easily find ready lexical semantic specification from their Ll (Chinese) to map onto their L2. To determine the effect of cross-linguistic influence on the development of bilingual lexicons, three groups of learners of different English proficiency levels were asked to perform a timed English semantic judgment task. The task contained word pairs shared the same meaning of Chinese in translation, but the semantic concepts were distinguished in English. The statistical and interview results indicated that Chinese semantic activation was found to influence the decision-making of two proficiency levels of the learners. The students of the intermediate and the high-intermediate levels might take advantage of the Chinese representations to interpret L2. However, the advanced learners could automatically activate only their L2 in the lexical entry for the task. The strength of lexical links to LI appeared to decrease in degree as the proficiency level increased. Pedagogically, the instructions of semantic comparisons and contextualized L2 input might be beneficial for the learners to reconstruct their language systems in order to fully develop integrated lexical knowledge in two languages.