Context cues are useful for listeners to normalize speech variability and achieve perceptual constancy. It remains unknown whether this normalization strategy is language-independent and can be generalized directly from the perception of first language (L1) to second language (L2). To answer this question, Experiment 1 in the present study asked Mandarin learners of Cantonese to perceive ambiguous Cantonese tones with context cues. The results revealed a significant Cantonese-tone normalization process in Mandarin learners, but the effect size was smaller than native speakers, suggesting that speech normalization required language-specific knowledge and thus it was refined gradually during L2 acquisition. The results also showed that even with effective context cues, Mandarin learners tended to give more high level tone responses, a tone also in Mandarin, implying that L1 phonological system interacts with immediate L2 context during L2 speech normalization. Experiment 2 revealed that L2 immersion but not overall L2 proficiency or L2 phonological proficiency facilitated L2 normalization process, indicating that L2 speech normalization improved with perceptual practice and needed more high-level L2 knowledge than L2 phonology.