Abstract: The simulation of the seam behavior is a key to analyze the segmental externally pre-stressed beam with finite element method. Based on the force characteristics of the reinforcements and concrete in different parts of the joint, a numerical model which can simulate the workings of the joint is presented and a nonlinear finite element program which can simulate the working process of externally pre-stressed concrete beams is developed. With the program, the factors of an experimental beam made by Angel C. Aparicio et al are altered and the flexural behavior of segmental externally pre-stressed beams is analyzed. The results show that the joint element has no essential distinction with the normal in the beam, the difference is only in the materials that work and define the rigidity of element; the ratio of ordinary steel bars has little effect on the flexural behavior of externally pre-stressed concrete beams with shorter segments; the initial prestress in external tendons, the shape of the tendons and the number of segments have effects on the flexural capability of the segmental externally pre-stressed beams.