The displacement,velocity and acceleration analysis of the general spatial 7R mechanism is discussed in this paper,fused on the method proposed in Ref.[2],an input-output algebra equation of the 16th degree in the tan-half-angle of the output angular displacement is derived.The derivation process and computation are considerably simple.A program written in Allanguage is used to derive the coefficients of displacement equations: therefore the amount of manual work is greatly decreased.The results are verified by a numerical example.The researches of this paper and Ref.[5]found a base for establishing an expert system of spatial mechanism analysis in the future.