Phase matching is one of the important keys for high-efficiency energy conversion in optical parametric chirped pulse amplification (OPCPA). With simulation on the OPCPA process of several conventional nonlinear crystals, it is found that the spectra of output signal from phase mismatched OPCPA is broadened, and the center of spectra is depressed. It is proposed that the phase mismatched OPCPA can be a novel method for spectra shaping of chirped pulses The parameters influencing the spectra shaping process is given. The amplifying characteristics with OPCPA phase mismatching for several conventional nonlinear crystals under degenerate, quasi-degenerate and non-degenerate conditions are compared.