The work aims to establish a method to simultaneously identify the nonlinear elasticity and non-linear damping properties in the packaging system. First, the motion equation of packaging system of single degree of freedom was deduced as Volterra nonlinear integral equation of first kind. The Landweber iteration regularization method was adopted to find the accurate solution of the Volterra integral equation in the noisy background. Since the number of the iterations had great effects on the accuracy of the solution, the L-curve criterion was used to determine the appropriate iteration number. After solving the Voterra equation, the free response data of the packaging system as well as the solution of Voterra equation was used to identify nonlinear elasticity and non-linear damping properties simultaneously. The accuracy of this method was investigated through a digital example. The method proposed in this paper can be used to effectively identify the nonlinearity of the packaging system.