This study aims to test the validity of Critical Period Hypothesis (CPH) by investigating the influence of starting age on Chinese English learners’ pronunciation. The study compares the degree of foreign accent of native Chinese English learners with different starting ages in learning English, in an attempt to determine whether early Chinese English learners could outperform late ones in terms of English pronunciation when exposed to an English-speaking setting. Furthermore, this research also proposes to investigate other possible factors that affect Chinese English learners’ pronunciation. Participants were asked to provide spontaneous speech samples through semi-structured interviews conducted face-to-face or via Skype. In addition, an additional read-aloud task was required to ensure a more thorough and in-depth interpretation. The final results run counter to the Critical Period Hypothesis as there appeared to be late starters who also achieved native-like pronunciation, and there was no significant difference between early starters and late ones in terms of pronunciation. However, the study also yielded some results suggesting that greater efforts and stronger motivations were required for late starters in order to achieve the same pronunciation levels as early starters’, indicating that starting age can be a sensitive rather than critical factor for second language (L2) pronunciation acquisition.