Poverty is one of the crucial issues in the world, particularly the developing countries in Southeast Asia. Each country seeks to increase the GDP per capita in order to reduce the poverty. To achieve this goal such policies have been made with different strategy. This study aims to investigate the determinations of poverty in OIC members countries and OIC Non members countries in Southeast Asia. The object of OIC Members Countries are Indonesia and Malaysia as well as Thailand and the Philippines for OIC Non Members Countries. This research used Fixed Effect regression with panel. The model consisting of the dependent variable and several independent variables including poverty, human development index, per capita GDP, government spending on education and health, Gini ratio and access to clean water. The results showed that the determinants of poverty in OIC Members Countries are HDI, government spending on health, per capital GDP, Gini ratio, and access to clean water. While the determinants of poverty in OIC Non Members Countries are HDI, government spending on health, GDP per capita, and access to clean water. The development of HDI is still very important variable.