Challenges in 21st century learning require teachers to improve their performance. Among the factors that influence teacher performance are the quality of the lesson plans and the supervision of the principal. The purpose of this study was to analyze the effect of the quality of the Learning Implementation Plan (RPP) and the supervision of the principal on improving the performance of elementary school teachers in Tebing Tinggi Distric. This research was conducted on teachers in nine elementary schools in Tebing Tinggi District with a population of 156. The sample used was 105 respondents Data analysis was performed using multiple linear regression method. The software used for analysis using SPSS 25.0. From the Unstandardized Coefficients for the variables of lesson plan quality (X1), Principal Supervision (X2), Teacher Performance (Y) a multiple linear regression equation can be made as follows: Y=13,291+0,316X1+1,159X2. The results of the analysis show that the teacher performance variable is influenced by the quality lesson plans and teacher performance. It can be concluded that the variables of the quality of the lesson plans and the supervision of the principal simultaneously have a positive and significant effect on the performance of teachers, with the existence of a quality lesson plan and the supervision of the principal which is carried out according to the procedures, the performance of the teacher increases.