The purpose of research is to analyze the effect of structure of third party funds (STPF), financing composition (FC), and non performing financing (NPF) on financial performance is measured by net interest margin (NIM). The methods used is descriptive and verification methods, with secondary data obtained from the financial statements period 2010 to 2015. The data analysis technique used is multiple linear regression, while hypothesis testing uses T -test and F -test. The results, it is concluded that the partially, STPF and NPF have negative and significant effect on NIM; While the CF has positive effect but not significant on NIM. Simultaneously STPF, CF and NPF have significantly effect on NIM with the level of 74.9%, while the remaining 23.1% thought is influenced by other variables not examined in this study.