The persistent photoconductivity(PPC) phenomena in n-type GaN Films grown by metalorganic chemical vapor deposition(MOCVD) have been studied. After using some testing and analysis methods, such as the double crystal X-ray diffraction(DCXRD), the photoluminescence(PL) spectra, etc, it is found that the issue which influences PPC in n-type GaN is not relative to the dislocations and yellow band(YB), and is caused by the doping level of Si most likely.