Abstract-The purpose of this study is to analyses mass concentration varied by its measurement of PM 2.5 and PM 10 according to the months and seasons. The study explored mass concentration in Ulaanbaatar, Mongolia with above schedule. It lasted from January, 2014 to April, 2015. The selected sites were Zaisan, Sansar tunnel, Kyokushu and Denj myanga within Ulaanbaatar.The study also analyses average mass concentration of PM 2.5 and PM 10 for the duration between October, 2009 and January, 2015.The study concluded that mass concentration of PM 2.5 and PM 10 increases during winter and decreases during summer. This variation depends on climate and pollution sources.