As a transmission type filter, phase-shifted fiber grating has the advantage of low cost and low additional loss, and it is a critical component in optical communication and sensor systems. As for chirped phase-shifted fiber gratings, the transmission peak wavelength and number are determined by the position and number of phase shift and the characteristics of the transmission peak are significantly affected by the amount of phase shift. Sectional apodization is used on chirped phase-shifted grating to obtain appropriate filtering properties for optical communication. The transmission peak characteristics are theoretically analyzed by transfer matrix method for chirped phase-shifted gratings with and without apodization. The numerical results show that the amplitude and phase response of the filter are improved and design requirements can be satisfied by proper apodization function and ratio. Meanwhile, the dependence of the transmission peak wavelength and depth on phase shift is diminished greatly and the impact of phase shift can be ignored by proper apodization. A method is proposed to generate millimeter subcarrier optical signal by using a double-channel chirped phase-shifted grating filter.