In real case, slope behavior shows the 3-dimensional movement and failure ; however the modeling methods for 3-D behavior are more difficult and need more variables. In this paper, 3-D coordinate system is divided into two 2-D coordinate systems. If two 2-D systems are used, 3-D system could be replaced by them. Therefore the analysis of slope behavior would be more easy and efficient. 3-D coordinate has the three variables, X, Y, and Z and in this coordinate, three variables must be calculated altogether. By the way, 3-D system is divided into three 2-D coordinate having two variables(X and Y, X and Z, Y and Z). However, in general, most sensing systems for slope are made to measure two angles(horizontal and vertical angles)and one length between a measuring point and another point. Therefore X and Y coordinate could be neglected and the other 2-D coordinates will give the perfect information for analyzing slope behavior. The purpose of this paper is to show slope behavior in 3-D not using 3-D coordinate system directly. It is proved by the data analysis of real slope behaviors.