The influences of second order Polarization Mode Dispersion (PMD) on light pulse are discussed from changing of the pulse shape and eye graph when considering second order PMD. The results by numerical simulation show that the second-order PMD components associated with depolarization of the principal states can cause significant system impairments that cause overshoot at the edge of pulse. By the same time the compensation method for second-order PMD are also discussed by theoretically and experimentally. The experiment results show that it is very effective to compensate second order PMD by using two stage PMD compensator.