Abstract: Contraction flow behavior contributes significantly to the orientation and structure of molecular in micro injection molding.Numerical simulation of 4:1 non-isothermal planar contraction flow was realized by using CFD software based on FEM—Fidap with appropriate boundary condition.Carreau viscosity model andquadrangle grid with 4 nodes are employed in simulation.The results show that the velocity of downstream fluid is higher than upstream,velocity grads obviously increase in contraction entrance,and pressure grad in downstream is higher than in upstream.The highest shear rate appears in the comer of contraction entrance.Comparisons were further carried between the velocity,pressure,shear rate distribution of simulation and simulation results in macro scale from Liang zhiming etal,and the characteristic agreement of micro scale analysis results with macro scale analysis results.However,temperature distribution is different between two results.The conclusion can be drew that the control equation and constitutive equation in macro scale contraction flow simulation is still compatible with isothermal micro scale contraction flow simulation study.The energy equation must be modified in non-isothermal micro scale contraction flow behavior study.