The present study attempts to investigate the difference of the use of modal markers in the Chinese e-mails by students of CFL (Learning Chinese as Foreign Language) at different proficiency Chinese levels. 35 CFL from the department of the School of Chinese Language and Literature, SooChow University, were divided into two groups according to their Chinese proficiency. The politeness of participants’ performance was evaluated based on two aspects: modal expressions and whole appropriateness. They were asked to write 8 e-mails on the topics provided, including two discourse styles (formal-informal) and four speech acts (suggestions, invitations, refusals, requests). Quantitative analysis revealed the differences between the two groups in the usage of modal expressions in e-mails, so as to distinguish the pragmatic awareness and pragmatic knowledge of Chinese foreign language learners at the different proficiency levels.