Interference joint is one of the most advanced assembly methods for camshaft. In this paper, the mechanism of camshaft interference assembly is analyzed by thick-wall cylinder model. Joining/tortion experiments are done to estimate the joining force and connection strength. The relationship between the torque capacity, joining force and interference of the camshaft is established by the experiment results. Joining force linear increase with the interference, and torque exponential increase with it. The plastic deformation characteristics of knurled teeth on the tube during the joining process are obtained by metallographic observation. The results reveal the metal line changes continuously of the knurled tube. The knurled tooth tip turns over after joining. And elastic limit would be reached in the extrusion region.