The 16-year-old rower won the medal in the C1-200m category, it said.
Earlier on November 5, she also scored gold in the C1-500m at the Asian Canoeing Championships.
Phuong, the youngest athlete at the event, finished with 2m20.376, followed by Fatemeh Karamjani of Iran with 2m26.046 and Lim Yuan Yin of Singapore with 2m27.291.
Nguyen Hai Duong, head of the national rowing team, said Phuong has been training very hard recently.
After returning home, she has moved to Haiphong to compete in the National Rowing and Canoeing Sprint Championships.
Born to a poor farming family in Vinh Phuc Province, Phuong began practicing rowing in 2012.
Three years later, she shined at the 28th Southeast Asian Games in Singapore in June 2015 when securing a gold medal in women’s C1-200m canoeing.
The gold medal was a pleasant surprise for Vietnam’s rowing team, who had not hope for any gold ahead tough competitors.