The second order Polarization mode dispersion of single mode fiber of 75 km is measured with Poincare spheré method, the statistical characteristics and influence of the components of the second order polarization mode dispersion (SOPMD) is analyzed. The parallel component and perpendicular component (also is called depolarization component) of SOPMD and PCD are analyzed, and the statistical properties of them are also analyzed. According to these it is found that the perpendicular component has a greater impact on pulse than that of the parallel component in mean. The research will be helpful for second order PMD compensation.