Task-Based Learning (TBL) is a student-centered, teacher-guided and task-performed teaching approach. This study was aimed to investigate the effects of task-based learning (TBL) in chemistry experiment teaching on promoting high school students’ critical thinking skills in Xi’an, China. To achieve the aims, a pre-test and post-test experimental design with an experimental group and a control group was employed. Students in the experimental group were taught with TBL, while students in the control group were taught with lecturing teaching methods. Five chemical experiments were selected, and 119 students aged at 17 - 19 voluntarily participated in the research which lasted one semester. The California Critical Thinking Skills Test (CCTST) was used as a data collection tool. Results showed there was an obvious significant difference (p < 0.05) in the dimension of analyticity in the experimental group after TBL, while there were no significant differences in the total score, the evaluation and inference of CCTST. The findings provide an effective way for chemistry teachers to improve students’ critical thinking analyticity skills.