The transmission spectrum of 1-D defect photonic crystal has been investigated by eigen matrix method.The results showed that:in the transmission spectrum,there are a number of narrow defect modes,and the longer the wavelength of narrow defect modes are,the greater the widths of narrow defect modes could be;when the incident angle increased,the longer the wavelength of narrow defect modes is,the smaller the intensity of narrow defect modes changes,the greater the location of narrow defect modes moves to the short-wave direction,and the greater the separation of S-polarized light narrow defect mode with P-polarized light narrow defect mode could be;by increasing the thickness of the periodic medium of 1-D defect photonic crystal,the wavelengths of narrow defect modes increases,and the mobile scopes of narrow defect modes also increases too.This study has made a significant sense of choosing and using the narrow defect modes.