Abstract: Three-dimensional optimization algorithm of the position solution about the six-SPS mechanism isobtained in this paper.The algorithm is based on the inverse solution of the positional problem in theform of nonlinear equations.As contrasted with the original algorithm of the mechanical positional solu-tion,this new method reduces former six-dimensional optimization to three-dimensional optimization.Therefore,the calculating speed is fast enough and the initial value of the method can be chosen easily.