Cognitive radar is a kind of new concept radar system which can solve the target detection problem under the complex environment. It can highly improve the radar performance through knowledge aided adaptive processing. In this paper, aimed at the crucial problems and the bottleneck which the traditional radar faces to, the concept and the configuration of cognitive radar are introduced. Then, the key algorithms in intelligent cognitive radar and the effects in improving the radar performance of these algorithms are discussed. Trough simulation and measured data analysis, it is proved that the proposed cognitive algorithm can markedly suppress the jamming and reduce the clutter remain so as to improve the signal to interference ratio.