Abstract: To predict the moment-rotation relation of CFST connections with blind bolts and flush endplate, a three-parameter exponential model is proposed based on ultimate moment resistance, on initial rotational stiffness, and on shape parameters. With the consideration of possible failure modes, the calculation method for ultimate moment resistance is proposed. Based on the component method, the model for initial rotational stiffness of the connection is proposed. The prediction values of the ultimate moment resistance and of initial rotational stiffness can be obtained only by the size and material properties of the connection. The comparison with the experimental results shows the correctness of the analytical model and of calculation method proposed. Furthermore, the proposed model is convenient and accurate and can avoid a lot of experiments and simulations. Therefore, the proposed model can be applied to the analysis and the design of connections in semi-rigid composite frames.