Abstract: In order to improve the quality in accurate tube bending,the spring-back of rotary-drawing tube bending is analyzed by the adoption of idealized elastic-plasticity deformation model,based on bending experiments and finite element simulations.Due to differences degrees of in deformation in different parts,two kinds of spring-back,created respectively by elastic-bending and plastic-bending,are generated.Through theoretical analysis,approximate formulas of springback are deduced,as are verified by making use of partial tube-bending experiments.The reason why the theoretical calculated values are smaller than those given by experiments is related to the nonuniformity in the bending force and in disregarding influence of friction.The formula is expected to be useful in practice through further amendment of more experiments.