The dynamic characteristic parameters of the Marx generator can be obtained by modal analysis. In this paper, the simulation analysis and modal experiment of the 32-stage modular Marx generator are conducted to evaluate its mechanical environment adaptability. Firstly, the finite element simulation model of the modular Marx generator is constructed, and the initial vibration modes are acquired. Secondly, under free boundary condition, the integral modal experiment, local modal experiment and transfer characteristic experiment are conducted respectively. In the end, the integral and local modal parameters are calculated. Results show that the 32-stage modular Marx generator has a first-order torsion at 23.58 Hz; the inherent frequency of local structure of the Marx generator is relatively high; the vibration transmissibility scopes on x, y and z axis are respectively 5-15, 6-10 and 10-35. These conclusions provide reference to design Marx generator in later engineering phase.