The invention provides a calculation method of elastic-plastic buckling load of an axially-compressed component. The method comprises the steps of (1) dividing the section of the axially-compressed component into a plurality of units to form section grids; (2) determining the buckling type of the axially-compressed component; (3) calculating the value of a corresponding tangential cut interval point, a buckling function value under the initial buckling load value, and the buckling function value under the tangential cut interval point according to the determined buckling type; (4) calculating the value of a cutting line point; (5) determining whether iterating is done according to the condition of convergence; if so, outputting the elastic-plastic buckling load; if not so, re-setting the initial buckling load value and the value of the tangential cut interval point, and returning to step (3). The method is small in calculation quantity, high in calculation efficiency, fast, wide in applicable scope and high in accuracy.