It happened around 9:00 p.m. on January 15th.
Investigators say the 27-year-old victim was travelling northbound on the subway as it pulled into the Logan Station.
That's when the man pulled her to the ground and grabbed her iPhone.
The man was seen on surveillance video fleeing the train.
The suspect is described as a black male, 20-24 years old, 5'5" to 5'7" tall with a thin build and facial hair. He was wearing a gray polo skull cap, light colored blue jean jacket and blue jeans.
Anyone with information is asked to contact Philadelphia police at 215-686-TIPS (8477).