Abstract: To calculate 3D well trail is very complex, and it is difficult to calculate resolution in axial load, in order to calculate the axial load in drill string in the well, the ability of side tracking should be calculated. In this paper, calculating well trajectory parameter by rain curvature method that is precise and includes effect of drilling fluid, and on the base of measure spot, we can get deviation angle, azimuthal angle, deviation change rate, azimuthal change rate, hole curvature and tangential, normal, and reverse normal in well hole at certain height.