The Thais won 12 golds for a total of 45 _ seven ahead of hosts Myanmar, who could only claimed seven titles yesterday.
The Thai team had led Myanmar by two golds at the end of Saturday's action. The biennial event ends on Dec 22.
Among Thailand's winners yesterday were three in track and field, three in weightlifting, two in karate-do and two in swimming.
In athletics, the Thai champions were Treewadee Yongphan (women's 400m), Sukanya Chomchuendee (women's pole vault) and Tantipong Phetchaiya (men's hammer throw).
Treewadee, who won in 53.11sec to secure her third straight title in the discipline, said she was surprised by her time. "I did not think I would make it," she said.
In the men's 400m, Srikharin Wannasa came in fourth while the gold medal went to Archand Christian Bagsit of the Philippines in 47.219sec.
Thailand also got silver from Supanara Sukhasvasti Na Ayudhaya in the men's long jump and bronze from Sawitri Thongchao in the women's shot put.
Surapong Ariyamongkol, secretary-general of the Amateur Athletics Association of Thailand, was disappointed by Supanara's performance because he had done much better in training.
"With three gold medals on the first day and four days to go, I am confident that we will meet our goal of winning 14 golds," he said.
In swimming, Thailand won two golds, three silvers and one bronze.
Nuttapong Ketin took gold in the men's 200m breaststroke in 2:13.32m ahead of compatriot Radomyos Matjiur.
Natthanan Junkrajang was first in the women's 200m freestyle in 2:01.03min, beating Singapore's Quanh Ting Wen.
In weightlifting in Yangon, Olympic silver medallist Pimsiri Sirikaew led Thailand's sweep of three gold medals.
In the women's 63kg category, Pimsiri lifted 99kg in snatch and 132kg in clean and jerk for a total of 231kg to comfortably take gold.
"I am very happy to win gold although my result was not so great," Pimsiri said.
In the women's 58kg, Sukanya Srisurat was crowned champion with an effort of 225kg (102kg in snatch and 123kg in clean and jerk).
In the men's 85kg, Pitaya Tibnok won gold after managing 151kg in snatch and 190kg in clean and jerk for a total of 341kg.
In petanque, Thailand claimed gold in the women's doubles after Thongsri Thamkord and Phantipha Wongchuvej defeated Cambodia's Sophorn Douch and Sreymom Ouk 13-4 in the final.
In the men's singles, Thailand's Wattanachai Sonthung lost to Myanmar's Than Zaw Oo 13-9 in the final.
In basketball, the Thai women are assured of gold after beating Malaysia 72-69 for their third straight win in a round-robin tournament.