This study aims to determine the effect of the Discovery Learning model on students' Mathematical Communication Skills and Self-Efficacy. The population in this study were all grade VII students of SMP Negeri 1 Sumbang. Samples were taken using a cluster random sampling technique that produced class VII C an experimental class with 35 students and class VII B as a control class with 36 students. The results of this study indicate: first, the results of posttest data analysis mathematical communication skills with α = 0.05 using the Independent Sample Test t-test obtained sig values. 0,000 which is 0,000 ≤ 0.05 so Ho is rejected, it means that Discovery Learning opposes students' mathematical communication skills. Second, the results of the self-efficacy questionnaire data analysis with α = 0.05 using the Independent Sample t-test obtained sig. 0.0135 which is 0.0135 ≤ 0.05 so that Ho is rejected means that Learning Discovery opposes students' mathematical self-efficacy. It can be concluded that the Learning Discovery regarding communication skills and mathematical self-efficacy of SMP Negeri 1 Sumbang students.