Native language background exerts constraints on the individual's brain automatic response while learning a second language. It remains unclear, however, whether second language immersion experience could help the brain overcome such constraints and meet the requirements of a second language. This study compared native Chinese speakers with English-as-a-second-language immersion experience (immersive English learners), native Chinese speakers without English-as-a-second-language immersion experience (nonimmersive English learners), and native English speakers with an ERP cross-modal MMN paradigm. The results found that English-as-a-second-language immersion could benefit speech perception for native Chinese speakers. In addition, both immersive English learners and native English speakers showed enhanced cross-modal MMN, indicating that second language immersion could help native Chinese speakers successfully integrate English letter-sound like native English speakers. The present study further revealed that English listening and speaking exposure in an immersive environment is important in English letter-sound integration for immersive English learners.