Since discovered in 1991, carbon nanotubes (CNTs) are widely used as potential components for nanoelectromechanical (NEM) devices due to their excellent mechanical and electrical properties. Experimental researches have discovered that the force leading a CNT to slip on a SiO2 substrate is almost constant in the range of contact lengths from 140 nm to 246 nm and increases with greater contact lengths. æThis study develops a theory based on the continuum mechanics to explain this observed phenomenon. æThe critical force leading the CNT to slip over the whole substrate is determined by using a beam theory within the bending, shear, and axial deformations of the CNT. æAt the stick-slip transition, the work of adhesion provides a concentrated force and a concentrated moment to compensate discontinuities in the internal forces and moments of the CNT. æThe modeling results obtained here provide the external force required for complete slip vs. a dimensionless parameter related to the shear stress and the contact length. æA comparison of the modeling result and the experimental data from the literature shows good agreement.