Abstract: The in-plane primary buckling and secondary bifurcation buckling load-displacement equilibrium paths of the elastic-plastic arches with same sections and different rise-span ratios are traced with a high-efficient tracing strategy. The elastic-plastic primary buckling load and secondary bifurcation buckling load under full-span distributed load,and concentrated load at the top of arch, and the primary buckling load under half-span distributed load are obtained. The calculation results show that the secondary bifurcation buckling is always the most dangerous buckling type when the arch is under full-span distributed load and concentrated load at the top of arch for elastic-plastic arch. The secondary bifurcation buckling will always happen before the primary buckling. For primary buckling load of the same section arches, the ultimate load carrying capacity of arch with 0.2 rise-span ratio is the biggest one under concentrated load at the top of arch. The ultimate load carrying capacity of the arch with 0.23 rise-span ratio is the largest one under half span distributed load and that of the arch with 0.1 rise-span ratio is the largest under full-span distributed load. For secondary bifurcation buckling load, the ultimate load carrying capacity of the arch with 0.2 rise-span ratio is the largest one under concentrated load at the top of archand that of the arch of 0.1 rise-span ratio is the largest one under full span distributed load. Finally the elastic-plastic ultimate load carrying capacity of elastic-plastic arch with different slenderness and rise-span ratios under full and half span distributed load were calculated and formulated for engineering reference.