This study aims to find out how teacher performance can be improved by examining the relationship between organizational culture, work discipline and job satisfaction on teacher performance. The sample chosen amounted to 244 people with the criteria of a Private High School teacher in South Tangerang Regency. This study uses Mixed Method Sequential Explanatory, namely the first research uses quantitative methods and then the second one is to deepen the research using qualitative methods. Further, Scientific Identification Theory of Operation Research in Education Management (SITOREM) is used to rank the improvement needed. The results of the study show that (1). There is a positive relationship between Organizational Culture and Teacher Performance with a correlation coefficient of r_y1 = 0.328 or 32.8% (2). There is a positive relationship between Work Discipline and Teacher Performance with a correlation coefficient of r_y2 = 0.796 or 79.6% (3) There is a positive relationship between Job Satisfaction and Teacher Performance with a correlation coefficient of r_y3 = 0.799 or 79.9%, (4) There is a relationship between Organizational Culture, and Job Satisfaction together with Teacher Performance, indicated by the correlation coefficient ry1230.555 =or 55.5%.