Hi, Jasin. There is no bus service from the airport to West Lake. The airport bus can only send you to Wulin Guangchang. You can get off there and walk south along Yan'an Rd. This is a famous business street. You can just wandering and turn right when you reach QIngchun Rd. You can see the Lake area. If you do not want to walk, you can take a city bus who are running southward or take a taxi within starting price. :)