To reduce the volume of ships， aircraft， and other engines， oblique pipe welding is used instead of elbow connection， and the end position in the pipeline system plays an important role in the welding alignment. First， the pipe axis was obtained by determining the seed cylinder and designing a nonlinear optimization algorithm. Then， the pipeline axis was obtained through diffusion reconstruction of the high-precision seed cylinder. Following this， the pipe edge was searched using the double curvature threshold search method， and the whole pixel coordinates of the end-face edge point of the pipe were obtained. Next， the subpixel coordinates of the end-face edge were obtained via elliptic fitting of the whole pixel coordinates extracted from the end face combined with the ray intersection method， avoiding the effect of the ambient light source on the subpixel coordinates calculated using the interpolation method. Finally， the spatial projection plane was reconstructed using the point-by-point least squares method and the minimal residual spatial ellipse was realized on the plane. The center of the elliptical circle of the space was the end of the pipe， and the projection plane was the plane where the end face was located， enabling accurate measurement of the head position. The experimental results show that the measurement accuracy of this method reaches 0.05 mm， and the angle measurement error is less than 0.1°， basically meeting the accuracy requirements of the head position measurement of an inclined pipeline， and presenting good guiding significance for the assembly of such pipelines.