A self-collimator planar spectroscopy shaping device for chirped pulse amplification (CPA): uses a spectrum decomposing system with CTSI construction, a spectrum synthesizing system with CTSI structure that is symmetrical to the decomposing structure, and a spectrum shaping system including an aperture and a planar reflector for spectrum shaping function design. The device accomplishes the following functions: firstly decomposing the spectrum of a chirped temporal pulse laser to a spectral domain; then shaping the spectrum in the spectral domain; finally synthesizing un-shiftily this shaped spectrum in the spectral domain into a temporal chirped pulse with a designed shape. The device has features of small size of concave reflector, easy fabrication, compact construction, little laboratory space needed, and cheap in cost, which it can be different types of configuration for different circumstance application, which it can be not only utilized in a general laser spectrum shaping and spectrum modulation, but also can be utilized for a high energy and ultra-high peak-power laser system in chirped pulse amplification with a large caliber and with a chirped pulse bandwidth of a few nanometers.