To avoid the large tensile stress ocurring in the main arch ring during the construction of long-span cantilever assembled reinforced concrete arch bridge，based on the Niuluhe Bridge with a net span of 195 m，an optimization calculation method of construction cable force was derived. The formal analysis was carried out in the general bridge structure analysis software Midas/Civil and the stress influence matrix in the construction process was extracted. According to the stress control conditions of the key section of the arch rib，the feasible region of the buckle force was determined by the formal calculation，and then the average value of the upper and lower limits of the feasible region were selected as the initial value of the buckle force，which was substituted into the iterative equation to determine the optimal construction buckle force，and then the anchor force was determined based on the principle of equal horizontal force. The results of numerical examples show that the cable force value of buckle cable construction is relatively uniform，the tensile stress in cross-section is less than 1.5MPa and the compressive stress less than 7.0 MPa during the construction of arch rib. The stress in cross-section can be calculated when the buckle and anchor cable are be tensioned once. This improves the work efficiency and can provide reference for the construction of similar projects.