Source rocks of the Alatanheli Group of Jurassic in well Zhunbao 1 in the Gerileaodou Sag of the Erlian Basin have been studied. Comparisons of geochemical features have been made between source rock and crude oil,indicating that the crude oil in well Zhunbao 1 originated from source rocks in the Alatanheli Group. The Alatanheli Group is the key exploration target in the Erlian Basin.