The Functional Assessment of Self-Mutilation (FASM) was first developed by Lloyd in 1997 to assess the functional reasons of non-suicidal self-injury (NSSI); it was then validated by Nock and Prinstein in 2004 and became widely used in self-injury literatures of the West. However, there was a lack of validated instruments to assess NSSI in the Chinese contexts. This study aimed to examine and validate the psychometric property of the Chinese version of the Functional Assessment of Self-Mutilation (C-FASM), which was translated from the 21-item FASM with further refinement. Among 825 recruited secondary school students, the data of 345 participants (mean age = 11.41 years), who reported having NSSI in the past 12 months, were involved in a confirmatory factor analysis. Although the Chinese data supported the four-factor model as proposed by Nock and Prinstein in 2004, it was also found that a second-order model had a better fit for the data. The Cronbach’s alpha coefficient for the overall scale was .94 and the overall scale score had significant correlations with NSSI related variables such as depressive symptoms, anxiety, impulsiveness, self-esteem and perceived social support. Both the reliability and validity of the C-FASM were sound, indicating that the C-FASM is a valid and reliable instrument for assessing NSSI among non-clinical Chinese adolescent samples.