Police have charged a man with drug supply after investigating the death of Sylvia Choi at the Stereosonic music festival last Saturday.

Daniel Dung Huynh, 25, from Punchbowl, was arrested at Auburn Police Station on Friday morning and charged with two counts of supplying a prohibited drug.

He was refused bail in Burwood Local Court on Friday afternoon.

Ms Choi, a 25-year-old pharmacist from Oyster Bay in Sydney's south, reportedly drank MDMA dissolved in a water bottle before falling ill about 5.15pm. She was pronounced dead at Concord Hospital about 9pm.