Entransy dissipation extreme principle is used to simulate the optimized laminar flow field in a curved tube numerically. Adjusted N-S equations with additional force are derived. The additional forces derived from the entransy dissipation extreme principle does not exist in real world and can be only used in calculations. When the governing equations change

different numerical result with same boundary conditions will be obtained

which is defined as the optimized flow field. The ordinary laminar flow fields in the same curved tube with the same boundary conditions are also calculated. The comparison between the ordinary flow field and the optimized one is made and the difference between the two flow fields is analyzed based on the field synergy principle. The result indicates that the additional force changes the flow pattern in the inner curved tube from ordinary laminar flow to symmetrical intense helical flow. The heat transfer performance evaluation criterion（PEC）value is more than 1.7 while the temperature gradient field becomes more uniform

and the cosine of field synergy angles around the boundary layer is increased

improving the surface heat transfer coefficient greatly. The optimized flow field improves the field synergy characteristics and enhances the heat transfer and can be utilized in development of heat transfer enhancement and energy saving techniques.