Lili Das gained her first international experience in 2016 at the Junior Asian Championships in Ho Chi Minh City , where she won the gold medal in the 800 meter run in 2: 0.64 minutes, as well as over 1500 meters in 4:29, 50 min. Thus she qualified in both disciplines for the U20 World Championships in Bydgoszcz , in which she was eliminated over 800 meters with 2: 13.45 min in the first round and in the 1,500 meter run with 4: 17.29 min in the final Tenth place. The following year she took part in the Asian Championships in Bhubaneswar for the first time and was fourth over 800 meters in 2: 07.49 min. In 2019 she finished 14th over 1500 meters at the Asian Championships in Doha in 4: 32.41 minutes and at the beginning of December she won the bronze medal over 800 meters at the South Asian Games in Kathmandu in 2: 08.97 minutes behind Dilshi Kumarasinghe and Gayanthika Abeyrathne from Sri Lanka.