By employing component method, an analytical model to predict the initial rotational stiffness of steel beam-to-column end-plate connections is set up. It is considered that the connection rotation is mainly induced by the deformation of the end-plate in bending, flange in bending, bolts in tension, column web in shear, column web in compression and column web in tension. The deformations of the end-plate and column flange in bending are estimated in plate-shell theory. Explicit formulae of stiffness are obtained for the end-plate and column flange with different stiffer configuration. The effective width used for the stiffness calculation is unified with that for the strength calculation suggested by EC3. When the stiffness of bolts in tension is calculated, the effects of connected plates under pre-compression on the deformation of bolts are taken into account. The comparison between the model and test results, other models, shows that the model is rational and more accurate. Moreover, the calculation process of the model is simple. Thusly it can be used in practical design.