Twisted ovaltube and twisted oblatetube were modeled respectively and the corresponding theoretical analysis and numerical simulation were carried out.The performances of flow and heat transfer in the two kinds of twisted tubed were studied comparatively. The results show that the heat transfer in twisted oblatetube is better than that in twisted ovaltube under the condition of laminar flow, howerer the flow resistance of twisted oblatetube is larger. According to the comprehensive factor,in twisted oblatetube the flow gets a good heat transfer enhancement.The twisted ovaltube is better than the oblatetube under the condition of turbulent flow.The property of heat transfer along the tube show that the optimal length of twisted tube is about 0.5 m.The geometical dimensions of twisted tube are of have great effect on heat transfer.