Abstract: In this paper，from the view of engineering application，under the condition that three control points formed an isosceles triangle，the relationship is studied between the error of P3P pose estimation methods and the input parameters.Firstly the relationship can be obtained by theoretical deduction.After that，through error statistical analysis and direct simulation validation，the following conclusion can be gotten.In the input parameter errors，the error of image coordinates and the calibration error of camera intrinsic parameters have more influence on the error of final pose estimation than the metrical error of objective model，which can be negligible.This conclusion is significant for the design and realization of pose estimation system.