Abstract: In this paper, first, the author has defined the similar complex vector, then regularized the given method of the similar complex vector spatial azimuth, and based on this worked out the general formula and a certain number special formulas of the similar complex vector. The author has yet gived the calculation rules of the similar complex vector, proposed the basic theorem (character) of the similar complex vector. At the base of this elaborated the similar complex vector principle in the displacement analysis of the spatial connecting red mechanism. Two calculation examples will be given in the end, and combined with these examples exposed the method of similar complex vector possessed the advantage that eliminated simply and easily, achieved aim not need or only need simple substitution.

Key words: Displacement analysis, Similar complex vector, Spatial linkage