Abstract: According to basic principles of polar stereographic projection, a formula calculation method is introduced in this paper by using spatial analytical geometry knowledge. It can take the place of hand-operation and get more accurate results. For instance, it can draw projection curve on computer screen while its equation had been referred from its attitude; it can get the attitude of the co-plane between two lines or the intersect line of two planes; it can calculate the interangle and the bisectrix of two lines or two planes; it can perform the transition between apparent dip and true dip or between dip and pitch; it can model the rotation of a line or plane around 8n axis, so the original attitude of a joint can be recovered. The last part of the paper is about the computer algorithm of joint intensity statistics and the iso-intensity diagramming. This method directly shows the relationship between structural factors so that it can be used for computer Aided Instruction(CAI). It also makes satisfactory application in practice because its accuracy reaches 0.0l℃.