Lan, 23, finished with a time of 52.63 seconds. She was followed by Nadeesha Ramanayaka of Sri Lanka in 53.24 seconds and another Vietnamese, Nguyen Thi Hang, in 53.29 seconds.
In April, Lan won the gold medal in the 400 meters hurdles at the 2019 Asian Athletics Championships in Doha, Qatar.
Also on Tuesday Vietnam’s Le Thi Tu Chinh won the bronze medal in the women’s 100 meters hurdles while Bui Thi Thu Thao won a silver medal in the long jump.
The Asian Athletics Federation invited 16 Vietnamese athletes to event in Chongqing from June 4-7.