The forward light scattering of the human′s static and deformed erythrocytes in Couette flow is analyzed by the theory of anomalous diffraction. The erythrocytes′ process of light scattering is simulated by Monte Carlo method based on the equal-volume or equal-surface model , the values of length in all three axes are worked out and the results are analyzed carefully. The result shows that compared with fraunhofer diffraction, this new kind of analysis is more accurate in precision.