This work is a feasibility study of high voltage AC (HVAC) and high voltage DC (HVDC) transmission option for the Association of Southeast Asian Nations (ASEAN) Power Grid (APG) interconnections. An optimal power flow, a minimum-cost power generation model, is developed in the MATPOWER simulation platform to perform this analysis. Electricity generation and consumption data are taken from the latest power development plans of individual ASEAN countries for the evaluation of optimal cross-border power flow through the interconnections. Results show that APG can enhance power generation from countries with abundant renewable resources to meet the growing demand at load centers in the ASEAN member nations. An annual cost is used as the output matrix for this study. The analysis results reveal that in some interconnections, implementing HVDC link instead of currently planned HVAC could be economically beneficial for the APG. The findings in this paper would serve as valuable references for the APG planners.