Abstract: 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 experimental modeling method and the IHBNID. The result of numerical simulation shows fairly good compatibility with experimental system on qualitative and quantitative aspects. This theory including experimental modeling method and the IHBNID demonstrates that it also can be applied to experimental systems with variable frequencies and motions, such as the period-doubling motion.