The knife-wielding man has been apprehended by the police.
According to reports, the man attacked people at Hechuan Road Station on the city's No. 9 metro line.
Police said the attack happened at 8:28 a.m. at the subway station in Minhang District in the southwest part of Shanghai, Xinhua news agency reported.
The injured people were hospitalised.
The station was temporarily closed following the incident.
It was later reopened.
The arrested suspected was identified as a 54-year-old man surnamed Shen.
The case is currently under investigation.