Can I buy the smart card from the hangzhou xiaoshan international airport?

Well, as I know, there is no service counter at the airport that can buy the transportation card. So I'm afraid that you need to purchase it at service centers in downtown area. One is located at No.20, Yan'an Road. You can go and see.
Besides, I remember that the airport doesn't provide sim card. You are also suggested to buy it in downtown. China Mobile and China Unicom are popular ones. Both of them have many branches in this city. You can easily find one nearby your living place.
Hope helpful!