Owing to their small volume, strong radiation resistance and fast time response, diamond detectors show the obvious advantage of application in nuclear radiation area. At early stage, diamond nuclear radiation detectors were made of natural diamond materials. With the development of chemical vapor deposition (CVD) diamond synthetic technology, the development and application of diamond radiation detector has been greatly promoted. In this paper, starting with the CVD synthetic diamond material, the impurities and defects that restrict the performance of diamond detectors, the synthetic process of CVD diamond, the characterization method of impurities and defects in detector grade diamond are analyzed systematically. Based on the performance indicators such as the product of carrier mobility and life, the charge collection efficiency of detector, etc., the effects of impurities and defects in CVD diamond on the performance of the detector are summarized. The application status of diamond nuclear radiation detectors abroad is introduced and the development prospect of domestic diamond nuclear radiation detectors is also viewed.