The principles of the microwave radiometric imaging system are discussed. For there are many factors which influence microwave radiometric imaging quality, the relationships among the radiometer spatial resolution,the radiometer sensitivity, the sampling interval, the antenna scanning speed and the integration time are analyzed. Then some corresponding experiments are made to examine the influence of two main factors: the integration time and the sampling interval. And the result proves that these factors restrict and effect each other. When the parameters of microwave radiometric imaging system are chosen, different situation must be considered. Thus, perfect image can be obtained.