Is it possible that i can get a taxi from Hang zhou airport to go to Xi tang ancient town? if yes, how much would it be?

It is almost impossible to take a taxi between the two places. Taxis only operated within one city, but the two cities belong to different cities.

Here are two alternatives for you: take the airport intercity shuttle bus to reach Jiaxing North Bus Station and then take Jiaxing public bus line 152 to Xitang directly. Or take the airport city's shuttle bus North Bus Station Line via HZ Jiubao Central Bus Station to reach Jiubao Central Bus Station, where you can find frequent buses for Xitang.

The bus to Jiaxing is 44RMB and the bus fare from Jiaxing North to Xitang is 7RMB. The bus to Central Bus Station is 20RMB and then the bus fare to Xitang is 38 to 42RMB.