<p>Purpose of this study is to investigate determinants factors of Commercial Banks’s net interest margin in Indonesia, Thailand and Philippines. This study uses quarterly panel data from 2010 until 2020. The OLS Equation Model was used to analyze the macroeconomic factors and banks' specific factors towards Net Interest Margin. The result showed that inflation rate as the only one factor from Macroeconomic factors and Overheard cost is one from Bank Specific factors which significantly affect Net Interest Margin in all of these countries. Other than that, valuable findings from this research shows that determinants factors which have significant impact from bank specific characteristics in each country are different. In Indonesia, Higher Size of operations, Risk Aversion and Income Diversification are determinants factor that can lower net interest margin. Bank in Indonesia have to manage their credit risk well, because this factor can potentially lead to higher NIM. Commercial Banks in Thailand and Philippines show opposite result. Larger size of operations and higher risk aversion, will lead to higher NIM. Market concentration plays a critical role to minimize NIM in Phillippines. So, regulator should maintain this condition. Because higher competition potentially lead to higher NIM in Philippines’s bank.</p>