The purpose of this study was to describe the mathematical critical thinking skills of seventh-grade students of SMP Negeri 4 Purbalingga based on learning autonomy. The type of this research was a qualitative descriptive study. Respondents in this study were students of Grade VII F who were selected using a learning autonomy questionnaire. The respondents grouped into three categories, namely students who had high, moderate, and low learning autonomies in which 2 students were then selected from each category. The data were collected using questionnaires, tests, and interviews. Data obtained in this study were then analyzed using the Miles and Huberman model which included data reduction, data presentation, and conclusions. Technical triangulation was also used in this study to test the validity of the result. The results of this study showed that respondents with high learning autonomy were able to master all indicators of mathematical critical thinking skills, namely providing simple explanations, building basic skills, making conclusions, and determining strategies and tactics. Moreover, respondents with moderate learning autonomy tended to master several indicators of mathematical critical thinking skills, namely building basic skills, making conclusions, and determining strategies and tactics. In contrast, respondents with low learning autonomy only mastered two indicators of mathematical critical thinking skills, namely building basic skills and making conclusions.