Which line should I take from hangzhou east railway station to Sijiqing subway?

The distance between the two places is far, so you can take the subway 1 line, then get off at Fengqi Road or Longxiangqiao Station and walk to Sijiqing.

Baidu map shows that the subway 1 line connects hangzhou east railway station and major areas in the city center, including Fengqi Road and Longxiang Bridge.

Fengqi Road and Longxiangqiao Station are interchange stations of subway 1 line, and also important traffic nodes connecting urban areas and Sijiqing business district. After getting off at these two stops, you can easily walk to Sijiqing business district without changing to other means of transportation.