In this paper, a 2D strongly disordered a zinc oxide (ZnO) thin film is modelled and simulated to investigate behaviors of ZnO random lasers. In order to observe the scattering and interferes of the electromagnetic waves (EMW), Maxwell's equations are solved for a transverse magnetic (TM) wave by using finite-difference time-domain (FDTD) method. Perfect electric conductor (PEC) boundary condition is used to truncate the FDTD problem space. The 2D random laser is formed with vertical aligned ZnO nanorods. The size and distribution of ZnO nanorods in the medium are randomly distributed in the air background medium. The intensity of modes and spectrum of ZnO random laser are observed for different EMW excitation values, and different numbers and radii of ZnO nanorods in the medium.