The performance of linearly chirped gratings is optimized by designing and changing the parameters of apodization functions, aiming at some issues such as the unexpectedly fluctuating group delay ripple (GDR) in chirped fiber Bragg grating (CFBG) which are applied to achieving all-optical dispersion compensation in 40 Gb/s optical communications. This method is proposed by selecting some apodization functions with different roll-off characteristics, using genetic algorithm to optimize the apodizing parameters, and combining with transfer matrix method to gain the linearly chirped gratings with low group delay ripple after 200 generations. The numerical results validate the superiority that the ripple occurring in valid bandwidth of flat reflection spectrum can be restrained by adopting asymmetrically partial apodization. Moreover chirped Bragg grating fibers are fabricated of which reflection spectrum bandwidth of 1.06 nm and its delay ripple no more than 45.60 ps, and can be used in dense wavelength division multiplexing system (DWDM) with high capacity.