Thien completed the 95km tour from Can Tho to Tra Vinh with a time of 2hr 19.38min.
He was followed by Cao Hoang Thinh of Bike Life Dong Nai and Phan Hoang Thai of Domesco Dong Thap.
There is no change in the overall ranking.
Quach Tien Dung of Military Zone 7 was on top clocking 13:56.29
Nguyen Pham Quoc Khang of Bike Life Dong Nai and Pham Minh Triet of Gao Hat Ngoc Troi An Giang were second and third, respectively.
Thai grabbed more 18 points to have a total 78 points and retained the position of green jersey holder after seven stages.
In the team rankings, Gao Hat Ngoc Troi An Giang, Bike Life Dong Nai and Go for Gold secured the top three positions.
The seventh stage today will be 100km from Ben Tre to Kien Tuong.