Abstract: Difference of arch rib stiffness based on two concrete-filled steel tube arch bridge standard of GB 50923-2013 and JTG/T D65-06-2015, 15 groups of steel tubes and concrete according to the method of two specifications were calculated. In order to analyze rationality of the two specifications of arch rib stiffness, the FEM analysis of ANSYS was used to simulate a single arch rib. Finally, a standard steel tube concrete arch bridge was used to establish the finite element model and analyze the influence of horizontal bracing on its stability. The results indicate that the error of the calculation result of the rigidity of the arch rib is within 10%. The single arch rib simulated by ANSYS using the unified theory is more convenient and faster than using the double-element method, and the result of simulation is more consistent with the test result. The stability coefficient of arch bridge by using "X" brace is 4.3%, 0.6% and 17.8% higher than that of "H" brace, "K" brace and "一" brace respectively. When the number of bracing increased from zero to 2, the stability coefficient of standard CFST arch bridge increased by 41.2%, and the rate of increase was the highest. The number of bracing continued to increase, while the improvement rate of stability coefficient decreased. The bracing built between the span of 1/4 and 5/8 can make the stability of CFST arch bridge achieve the best effect.