The exercise will cover areas in Phitsanulok, Khon Kaen, Chon Buri, Rayong and Chanthaburi provinces from Feb 11-21.
The primary participants in Cobra Gold 2014 will be about 9,000 troops from the United States and 4,000 from Thailand. Other participants include 80 troops from Singapore, 120 from Japan, 300 from South Korea, 160 from Indonesia and 120 from Malaysia.
China will send 25 troops to offer humanitarian and civic assistance.
Eleven other countries will send observers - Myanmar, Laos, Vietnam, China, South Africa, New Zealand, the Netherlands, Ukraine, Russia, Pakistan and the United Kingdom.