Laos joined ASEAN in 1997 and has practiced the Common Effective Preferential Tariff (CEPT) scheme under ASEAN Free Trade Area (AFTA) since 1998. To estimate the effects of AFTA on international trade in Laos, this paper has built a gravity model to analyze the specific effects of AFTA on aggregate international trade volume, import and export in Laos by using bilateral trade data between Laos and 29 partner countries during 2000 and 2012. Binary variables and the size of economy of AFTA are chosen to be the two variables reflecting the effect of AFTA on international trade of Laos. Results indicate that AFTA has positive effects on aggregate international trade volume and import while negative effects on export in Laos.