Chirp matched optical parametric chirped pulse amplification method (OPCPA) has been proposed by studying the variation of OPCPA gain spectrum with the pump optical center wavelength. Taking nonlinear KDP crystal as an example,the temporal and spectral gain characteristics of the chirp matched and mismatched OPCPA methods have been studied. Furthermore,the changes of the temporal and the spectral profiles before and after the OPCPA have been analyzed in details. The results show that the gain narrowing phenomenon becomes significant for the chirp mismatched case. However,the gain spectrum width is greatly increased by using chirp matched method,eliminating the gain narrowing phenomenon.