Light propagation in two-layered skin mode was simulated with Monte Carlo calculation using two diferent phase functions to give the photon-RBC (red blood cell) scattering angles for comparision. Results include:the intensity distribution of detected photons, the dependence of photon number on frequency shift, the dependence of total frequency shift and mean frequency shift on RBC concentration. The results show that the linear dependence of total frequency shift on RBC concentration is valid only when the concentration is low. At low concentration the first moment F and the first weighted moment (Δf)s of the spectral power density of intensity fluctuation reflect RBC's mean velocity while at high concentration they reflect RMS (root-mean square) velocity.