In order to investigate the mechanical properties of bolted joints with exterior diaphragm in different structural forms，this paper is based on the monotonic loading test results of bolted joints between circular concrete filled steel tubular（CFST）column-H-shaped steel beam with exterior diaphragm. Appropriate constitutive models of concrete and steel are adopted. Subsequently，finite element software ABAQUS is used to build an elaborate 3D solid finite element model（FEM）of the joints. By comparison，it is found that the numerical results agreed well with the mechanics characteristics and failure forms of the experiment，verifying the reliability of the FEM. Finally，taking a traditional welded exterior diaphragm plates rigid connection joint as the benchmark，the numerical simulation of bolted joints with exterior diaphragms under different construction measures are compared. The analysis results show that when four rows of bolts are provided on the structural diaphragms，the steel beam web is welded with stiffeners，and the top and bottom diaphragms are also added with stiffeners，this type of bolted joints with external diaphragms can achieve initial rigidity and flexural capacity of fully welded exterior diaphragm plates rigid connection.