Abstract: The geometrical parameters of a sprocket and a saw chain may usually not fulfil all the engaging requirements due to different designs, error when made, wearandtear and deformation during its use. A saw chain is supported on a sprocket mainly with three conditions, which are toothside supporting, toothtop supporting and ring　contour supporting. The influences of deviation of four pairs of parameters on engagement were analysed in this paper, which are toothwidths of drive link and sprocket, toothtop highness of sprocket and notchhighness of side link, diameter of sprocket ring contour and toehighness of side link, groove angle of sprocket and wedge angle of drive link. The influences of them are similar to the influence of pitch deviation to a great extent, and the formulas corresponding to each other are also built here.