Authorities say the accident happened around 12:30 a.m. at 11th and Market Streets along the northbound side of the SEPTA Paoli/Thorndale Line.
It is not clear how the woman fell onto the tracks but police say, crews had to pull the victim from under the train.
They say she suffered head and leg injuries from the fall and was not injured from the train.
She was taken to Jefferson University Hospital and is listed in stable condition.
Police are investigating.