This study aims to analyze the effect of applying the reciprocal teaching approach in an effort to improve students' critical thinking skills in the XI-IOP B class of SMK 1 Cimahi in the matrix material. This research is a type of classroom action research consisting of 2 (two) cycles based on the mathematics teacher's syllabus in class XI-IOP B. Each cycle is based on the objectives to be achieved in learning. The cycle in this study includes the following procedures: (1) Planning; (2) Acting; (3) Observation and evaluation; (4) Reflection. Based on the results of research conducted on class XI-IOP B students of SMK 1 Cimahi that the use of the reciprocal teaching approach can improve mathematical critical thinking skills, namely: (1) the response and learning outcomes shown by students in the second cycle are very good and (2) Tests of mathematical representation ability of students in each cycle experienced a good improvement, until the last cycle showed 87%. Based on the results of the test it can be seen that there are only 4 students out of a total of 29 students who have grades below 65. Learning by applying the reciprocal teaching approach is very effective to be used in the learning process.