The SIOP mode is a teaching mode of “combining language learning with application ability” and “combining subject knowledge with thinking development, which provides a feasible way for learning language knowledge and cultivating thinking ability. Based on college English, a language course, this study selects 157 freshmen from a provincial key university, and divides them into experimental class and control class, using the SIOP mode and traditional mode to teach respectively. After one school year, the results of pre-test and post-test in two classes show that the SIOP teaching mode plays a positive role in promoting college English learners Critical Thinking ability. The research results have certain enlightenment and reference value for the localization application of the SIOP teaching mode and the cultivation of Critical Thinking ability for the undergraduates in China.