Abstract: A numerical method, named"Method of fictitious Griilage" Which was advanced by Prof. Huang Wen-Xi, can be used to aualzye the static and dynamic structural actions of arch dams and shells, It is better than other methods (e.g. Trial Load Method,Finite Element Method) especially in analysis of arch dams. This paper expounds computational methods of the fictitious grillage, and develops a program computer program which can Compute defor rmations and stresses of arch dams. Examples have proved that this method has many advantages. Therefor, the method should be spread and applie.