Abstract:In this paper, the author demonstrates that the maximale erroe of deflection for cubic solution of perturbational algorithm is near the lower fulcrum. This paper puts the formula of calulate the maximale erroe of a deflection and the erroe of level tension. Based on the above work, the discussion was made of the precision for perturbational algorithm of a cableway. And, besides, this paper puts the formulas of calulate the absolute erroe of a detection for once and cubic solution of perturbational algorithm, so that the height is under control in the production.