International education has surged ahead of tourism to become NSW's highest service export industry by nearly $2 billion, and the number of overseas students at the state's universities has grown by more than 30,000 over two years.

The total value of international education to the NSW economy has jumped nearly $1.5 billion since 2013, from $5.5 billion per year to $6.96 billion in 2015, NSW Department of Industry figures based on Australian Bureau of Statistics data show.

The state is now drawing about a third of Australia's total international education earnings, estimated at $21 billion per year.

The value of the sector to the NSW economy is now significantly higher than tourism, which was worth $5.2 billion in 2015.