ANALYSIS OF MATHEMATICS CRITICAL THINKING ABILITY BASED IMPLUSIVE AND REFLECTIVE COGNITIVE STYLE. The purpose of this research was to describe the critical thinking ability of based on impulsive and reflective cognitive style. The research method used a descriptive qualitative approach. Data was taken with a the ability of matematics critical thinking test, Matching Familiar Figure Test (MFFT) to measure cognitive style, and interview. The student's test result was analysed, then four students were selected, the two of them are impulsive cognitive style, and the others are reflective cognitive style, for qualitative analysis. The result showed that the ability of mathematics critical thinking students with reflective cognitive style is better than students with impulsive cognitive style on the indicators of understanding the problem, giving logical reasons with various relevant concepts and connecting between concepts, and making conclusions. While on the indicator of solving problems with the concepts, students with impulsive cognitive style is a better than students with reflective cognitive style.