The purpose of the study was to analyze the items about students' mathematical critical thinking skills by using Graded Response Models (GRM). This research is a type of qualitative research with a descriptive approach. The research subjects here were VIII grade students of MTs Al Muhajirin Panjang 2018/2019 school year, totaling 30 students by means of purposive sampling. Data collection techniques are carried out by written tests (essays) and interviews. The data analysis technique is using the Graded Response Models (GRM) test, which is then combined with data reduction, data presentation, and conclusion drawing. The results of the study show that students with high ability categories can generally say that students can work on mathematical critical thinking tests well according to mathematical critical thinking criteria in accordance with indicators of critical thinking questions. Students with moderate abilities can generally be concluded that students who have moderate abilities have not been too capable of working on mathematical critical thinking tests well according to mathematical critical thinking criteria. As well as low-ability students in general it can be concluded that students who have low ability have not been able to at all work on mathematical thinking test questions properly according to mathematical critical thinking criteria.