Incremental harmonic balance nonlinearity identification(IHBNID) method has already been applied to the experimental modeling method for single-degree-of-freedom dynamical equation and shows reasonable match between numerical simulation and experimental system.This paper aims to apply the IHBNID to multi-degree-of-freedom nonlinear parametric and forced excitation vibration system.So the experimental platform of L-shape beam system is set up and the dynamical equation of the beam is built with the experimen...