Abstract: Analyzed in the essay are the existing problems for measuring the end pout defect and radial deviation of the weld steel pipe.Accordingly a quite new measurement method is proposed,and a special tool is designed.The operation principle of the tool is described as follows.Setting a reference circle in the space outside the outer surface of the steel pipe based on which the virtual contour line of the ideal circle of the pipe is established.Then getting this ideal contour line calibrated as the zero point to obtain the dimensions of the end pout by means of measuring the distance between the outer surface of the pipe and the said ideal contour line.Thanks to the measurement method,the problems of irrationality and inaccuracy as staying with the currently-used measurement method is fixed,and moreover it no longer needs to prepare huge quantity of the template and the reference block.The said measurement tool is suitable for measuring pipes with end pout defect,and end and body radial deviations,having high economy and generality.