It is very important to determine the relative ubiety and combination of discontinuities. Besides traditional projection on equatorial plane and numerical methods,a new method,coordinate projecting method,can be used in stability analyses of the blocks coordinate projection. It is important to simplify curved discontinuities as the collection of limited small planes when analyzing curved discontinuities. The Qingfeng cavities in Shepandao is given as an example to analyse curved discontinuities with coordinate projection.