In the second language acquisition domain, researchers have devoted tremendous efforts to studying the relationship between L2 learning and some socio-affective factors, such as anxiety, motivation, etc. However, little research has been done to examine whether and how perfectionism, a psychological trait, affects L2 learning and L2 performance. The present study aims to fill this gap and investigate the relationship between the level of perfectionism and L2 performance among Chinese EFL college learners. Two specific questions are raised: (1) What is the relationship between perfectionism and L2 writing performance in terms of linguistic complexity, accuracy, and fluency? (2) What is the relationship between the six dimensions of perfectionism (Concern over Mistakes, Personal Standards, Parental Expectations, Parental Criticism, Doubts about Actions, Organization) and L2 writing performance in terms of linguistic complexity, accuracy, and fluency? To answer these questions, forty second-year students from Guangdong University of Foreign Studies majoring in English participated in the present study. The participants were required to compose a piece of English argumentative writing on the online system and then complete a 35-item Multidimensional Perfectionism Scale online immediately. The collected data were then processed and analyzed through SPSS (v. 17). The results of the analysis revealed that: (1) one of the measures of syntactic complexity has a significant negative relationship with perfectionism; (2) Personal Standards, one of the six dimensions of perfectionism, has a significant negative relationship with the participants' L2 writing performance; and (3) both Parental Expectations and Parental Criticism are found negatively correlated with the fluency aspect of the writing performance and the relationships have a significant effect. The implications of the findings are suggested for pedagogy and L2 learning.