Abstract: The present study took three experiments to explore the effects of tonal language experience on perception of Mandarin tones by Chinese-as-a-second-language speakers. The subjects contained some native Thai speakers who have tonal language experience and some native Russian speakers who have no tonal language experience. In experiment 1 and experiment 2, the tone perception task was used to investigate the perception of Mandarin tones by subjects with primary and intermediate Chinese proficiency respectively. In experiment 3, the tone perception assimilation mode of the native Thai speakers with primary and intermediate Chinese proficiency was investigated. Combining the results of the three experiments, it was found that the tonal language experience had played a promoting role in the tonal perception of Chinese as a second language, which was realized by the native tonal speakers' perceptual assimilation mechanism of mandarin tones. In addition, the perception and assimilation of mandarin tones by Chinese-as-a-second-language speakers were not significantly regulated by their Chinese proficiency, whereas the second language learners' perception of mandarin tones was restricted by the characteristics of mandarin tones themselves.