本文将思辨能力作为最重要的自变量，语言因素为中介变量，综合考察思辨能力对二语写作的直接影响，及通过其他语言因素对二语写作形成的间接影响。所构建的理论模型包含一个结构模型与五个测量模型，共含有5个潜在变量与13个观测变量。被试为来自4所省属高校9个自然班的232名英语专业三年级学生。研究发现，思辨能力及语言因素对二语写作具有整体预测力，能够解释一定比例的二语写作成绩变异；思辨能力对二语写作有直接影响；思辨能力通过不同路径对二语写作水平具有间接影响。研究表明，思辨能力对二语写作具有一定的解释力，此发现不仅可以开拓相关领域的研究视野，而且也启示我们在二语写作教学中关注语言因素贡献的同时，还应重视思辨能力在二语写作中的积极作用。

This study examined the direct and indirect effects of critical thinking skills (CTS) on L2 writing (L2W) by taking CTS as the most important independent variable and other linguistic variables as mediators. The theoretical model includes 1 structural and 5 measurement models, involving 5 latent and 13 observable variables. 232 third-year English majors from nine intact classes of four provincial universities in China participated in the study. Three major findings emerging from the quantitative analysis are as follows: CTS are found to exert total effects on L2W via linguistic variables; CTS show direct effects on L2W and CTS have indirect effects on L2W via linguistic variables. The findings broaden the visions of related fields and call for attentions to the contributions of CTS as well as linguistic factors to L2W.