The geometrical parameters of rock discontinuities are a foundation for simulating network of rock discontinuities and obtaining rock’s mechanical property parameters which are in accord with reality.This paper puts forward a calculating method that could obtain rock discontinuities’ dip direction and angle through inversion,in which method,firstly,the angle between rock discontinuities’ trace and the set coordinate axis in local coordinate system can be got through simple measurement,then the situation of rock discontinuities are transformed into two-dimensional problems from three-dimensional problems through the transition matrix of local and global coordinate system,finally,the rock discontinuities’ dip direction and angle can be gave by back-calculation.The generalized H-H method for trace length estimation,joint interval counting method and calculating method for connectivity rate of rock discontinuities under two-dimensional assume are introduced.Practice has shown this method is simple in use,reasonable in application,so has good practical value.