Abstract: Previous studies have suggested that the second language is acquired through its interaction with native language. Behaviorally, there are interactions between the native language and the second language in the processing of visual form, phonology, and syntax. The two languages also interact in terms of the neural organizations. Specifically, native language experience shapes the neural mechanisms of the second language, and the second language learning in turn affects the neural mechanisms of native language processing. The cross-language interaction is modulated by several factors, such as learner-related factors, linguistic factors, and task-related factors. Using both brain imaging technologies with high spatial resolution and electrophysiological techniques with high temporal resolution as well as cross-sectional and longitudinal paradigm, future research should systematically examine the cross-language interactions at multiple levels (e.g., word, sentence and passage) in terms of neural organizations and their dynamic changes during the course of the second language learning.