The aim of this research was to determine the germination ability of seeds and seedling vigor of three populations of Mountain thyme (Thymus kotschyanus) species using priming methods. A factorial experiment was conducted based on a completely randomized design with three replications in Research Institute of Forest and Rangeland, Tehran, Iran in 2016. In this experiment, factor A was: three populations of T. kotschyanus as Tehran, Gazvin and Zanjan, and, factor B had 6 levels of priming as: osmopriming [polyethylene glycol (PEG) 0.6 and 0.9 MPa], hormonal priming [gibberellic acid (GA 250 and 500 ppm], matrix priming (perlite), Hydro priming (distilled water) and control (without priming). The primed seeds were sown on the surface of the pots and growing them in the greenhouse conditions, the emergence traits including the percentage and speed of emergence, root and shoot length, seedling length, seedling vigor index, seedling fresh and dry weight, root shoot length ratio and seedling dry matter (DM%) were measured. The results of variance analysis between populations showed that the Tehran population with average values of 64.98% sprouting and 4.98 seedlings sprout/per day, had the highest emergence appearance and speed of emergence, respectively. In comparison between treatments, the highest value of speed of emergence (5.40) obtained by using PEG 0.6 MPa. The highest stem and seedling’s length with values of 65.7 mm and 31.4mm were related to hormonal priming GA (250 and 500 ppm), respectively. The highest seedling fresh weight (39.44 g) was obtained by hydropriming. According to the results of this research, it was proved that the methods of osmopriming (PEG), hormonal priming (GA) were effective priming methods Manuscript profile