When executing radiotherapy through Californium Neutron Knife, it is important to build Mathematics Model of Spatial Point and Plan Linear Programming of Radiotherapentic Dosage. In this paper, through frontal and side two-dimensional images of applicator, location-wire and human body reference point, we can get the two-dimensional coordinates of every point on these frontal and side images. By three-dimensional coordinates rebuilding, three-dimensional coordinates of every point under fixed coordinate system are obtained. And then, through coordinate transfer, we can get the total radiotherapeutic dosage of any spatial point that radioactive sources have stayed. The clinical result shows that this method for therapeutic plan establishment is reasonable and effective.