Influence of polarization mode dispersion (PMD) and group time delay ripple of the chirped fiber grating on dispersion compensation were investigated in this paper. It is shown experimentally that ripple of polarization-dependent differential group delay (DGD) has very similar variation behavior with the ripple of group delay (GD) in their spectra, though the former amplitude is about 40 times higher than the later. The minimum period of the ripples was measured to be 0.024 nm. A simplified theory is proposed to explain the similarity qualitatively. Simulations show that PMD and DGD ripples bring harmful influence to the dispersion compensation using the chirped fiber grating in high-speed optical transmission system. The relation between the incident polarization direction to the principal states of polarization (PSP) and the power penalty was calculated both by an approximate formula and numerical simulation. Simulations on eye patterns show that PMD of the linear chirped fiber Bragg grating (FBG) lowers the effectiveness of its dispersion compensation and worsens the performances of the communication in longer transmission length.