This study presents an attitude and opinion of Thai firms concerning the Trade Liberalization Agreement between ASEAN-China(ACFTA). The 680 questionnaires were distributed to the top and middle managers in Thai companies which have been importing from or exporting to China. The rate of response was 95.9 percent from 652 returned questionnaires were By category, 300 questionnaires were sent to importing companies and 277 of them were returned with a rate of response of 92 percent Furthermore, 380 questionnaires were sent to exporting companies and 375 questionnaires were returned with a rate of response of 98.7 percent. The results show that Thai SME firm operations are impacted in the short-term period and large firms in the long term. The adaptive strategy is focusing on exporting of unique Thai products and building strategic alliances with Chiness firms, including changing from competition to cooperation. The study also provides recommendation for enhancing a sustainable competitive advantage for Thai firms.