The measuring technology of moment of inertia based on Hilbert-Huang Transform ( HHT) is conducted to improve the measurement precision of the moment of inertia of large rotary body by the torsional pendulum method and to overcome the disadvantages of the traditional linear measurement model and the periodic method for calculating the moment of inertia. A nonlinear measuring model of moment of inertia considering friction resistance moment is formulated. On this basis of the model, the principal component of angular displacement is extracted by the empirical mode decomposition and the instantaneous damping coefficient and instantaneous undamped natural frequency are identified by Hilbert transform. The nonlinear model parameters are fitted by the least square method, and the moment of inertia is calculated accurately. A system for measuring the moment of inertia of a large rotary body is developed, and the rotational inertia measurement tests verify the feasibility of calculating the moment of inertia based on HHT are implemented on different combinations of standard parts. The measurement results of a large number of standard parts show that the relative error of the system is less than 0. 2% , the measurement precision of the interia using HHT is observably better than that of the traditional period method.