Abstract: The slip strain of adhesive layers is usually assumed to be linearly related with the interfacial shear stress in solving problems of slip effect for laminated beams. However, for laminated beams connected by coulomb friction, slippage occurs only when the interfacial shear stress exceeds the resistant friction stress. To study the mechanical characteristics of laminated beams, this paper deduces the shear stress calculation formula of a section considering interfacial friction. The mechanical condition and development path for slippage are determined. At last, the slip length and its influence on laminated beams are solved by means of transfer matrix method. Compared with the results calculated by ANSYS, the proposed algorithm is more accurate and efficient; Slippage destroys the integrity of a section and increases local bending stress. The influence of slip effect on the internal force of structures should be considered based on the slip state.