The Rain Classroom, grounded in the theory of connectivism in the digital era, is a mobile-supported tool for blended learning. This tool renders synchronous and asynchronous teacher-student interactions through dual-channel teaching in and out of class. In the study, the Critical Thinking Skills Survey (CTSS) was adopted to measure the critical thinking skills (CTS) of 112 first-year undergraduates majoring in English in mainland China. A pretest-posttest non-equivalent two-group quasi-experimental design was applied to compare the CTS of those learners of English as a second language (L2) instructed under the Rain-Classroom-based intelligent learning system with those taught by the traditional lecture approach. The mixed results indicated that the intelligent learning system had a positive effect on students’ overall CTS development with significant improvement in the interpretation subscale but had almost no influence on the evaluation and self-regulation subscales. The intelligent learning approach in this study is empirically meaningful in students’ CTS enhancement, but further research is warranted to make this system more efficacious in facilitating L2 learners’ CTS.