Research on the skylight polarization pattern plays an important role in the studies of the satellites or cruisers navigation using nature polarization pattern characteristic. A method of calculating the skylight polarization was proposed,which solved the vector radiative transfer equation (VRTE) of plane parallel atmosphere based on discrete ordinate method to get the Stocks parameter. Simulation results manifest that the difference of electric vector directions calculated by VRTE and Rayleigh Scatter experience formula are within 10%,and the VRTE method can obtain more accurate polarization degree. By comparing the solution of different wave-length,the polarization effect of blue light are stronger than red light,which provides an evidence for choosing the wave length of atmosphere scatter sensors.