In order to make the N-shaped boom develop smoothly in the space structure， the mechanical properties of its winding process are analyzed. Based on the covariant basis vector method， a theoretical model of the strain energy of a isotropic single tape spring during winding under pure bending conditions is established， and the theoretical model of the bending moment is derived by using the principle of minimum potential energy， and then the bending moment of the N-shaped boom is derived by fitting the curvature. Four N-shaped boom samples are developed and an experimental platform is built. The tensile force of the four N-shaped booms during winding is measured （HP-10） for 5 times by using a digital display push-pull meter， respectively. And the peak torque is calculated. The result shows that the deviation between the experimental value and the theoretical value is no more than 8.83% and the average deviation is 2.813%， thus the accuracy of the theoretical model is verified. This study can be used to analyze the peak moment of the super-elastic boom in pure bending state， which is of great significance for the design of the super-elastic boom.