Highly stabile single mode and multi-mode random lasing emissions were observed from ZnO nanorods array prepared on glass substrates using chemical deposition technique. By varying the post-growth-annealing time, nanorod diameters between 54 and 78 nm with population densities between 75 and 95 nanorods/µm2 were obtained. Depending on the population density and diameter of the nanorods, single, double and triple random lasing emissions were observed with lowest threshold of 209 mJ/cm2. Furthermore, the lasing threshold showed an obvious dependency on the nanorods density. The lasing emission maintained its wavelength with increasing pump power, indicating high stability of the lasing mode(s).