Another gang member, 21-year-old John Caratozzolo of Melton South, then kicked Cao in the head.
Justice Harper sentenced Caratozzolo, the attack's ringleader, last month to 15 years with a minimum of 10 years.
After attacking Cao, the teenager was involved in another attack on an Indian man the same night.
The youth will serve six years before being eligible for parole.
There have been a string of attacks on Indian students in Melbourne and Sydney over the past three months. The assaults led to an uproar in India. The Australian government has been assuring the safety of the Indian students. Nearly 100,000 students from India are enrolled in various courses in Australia.