This study was conducted to determine the biological charateristics of flowering and fruit development of ‘Bi Ro hat lep’ durian in Tan Binh commune, Phung Hiep district, Hau Giang province from August 2018 to July 2019. An experiment was implemented using seven ‘Bi Ro hat lep’ durian trees at the age of 8-year-old, grafted on ‘Kho qua xanh’ root stocks. Results showed that anthesis occurred within 12 days with a peak appearing in day 5, primarily at 16:00 to 17:00. The average fruit set rate was 87%. Fruit development process took place within 96 days after fruit set (DAFS). Young fruit abscission occurred mostly from 0-14 DAFS (42,2%). Durian fruit developed over three stages, i.e. slow (0-28 DAFS), fast growing (28-70 DAFS) and the mature-ripen stage (70-96 DAFS). Fruit flesh started to grow from 42 DAFS. Fruit reached to the maximum growing rate on 56 DAFS. At harvesting time, average fruit weight was 2,298.0±503.1 g, with an edible portion of 27%. The percentage of seedless fruit was 63%. Wet core, a kind of physical disorder, appeared at 70-96 DAFS. The phenomenon was observed on 14,8% of locule/fruit and 13,1% of aril.