Introduction: Total environment 24 % of all estimated global deaths are linked to the environment. As of 2022, Ulaanbaatar has a population of 1,691,800, vehicles 435,725, thermal power plants 4, market and shopping centers 111, factories 13,465, and 225 gas stations. Also, 1.5 million tons of waste are generated annually, 1135.6 tons of coal are used, and environmental pollution is increasing year by year. Therefore, it is necessary to investigate the heavy metal contamination of the soil of Ulaanbaatar city and protect the health of the population. Purpose: To determine heavy metals pollution in the soil of Ulaanbaatar city Materials and Methods: We used descriptive research design in this study. Secondary data from Meteorological and Environmental Monitoring Department was used. The content of heavy metals such as lead (Pb), mercury (Hg), chromium (Cr), and cadmium (Cd)) in the soil was evaluated in comparison with the maximum permissible amount specified in the MNS 5850:2019 standard. Statistical analyzing was calculated using SPSS-25 software, and p<0.05 was considered statistically significant. Results: The average concentration of heavy metals in the soil of residential areas of 9 districts of Ulaanbaatar city is cadmium 0.43 mg/kg (min=0, max=26.6), mercury 0.22 mg/kg (min=0, max=4), chromium 11.2 mg/kg ( min=0, max=1609.6), lead is 24.4 mg/kg (min=0, max=257.2). Cadmium concentration in soil Bagakhangai (25%), Baganuur (19.7%), Khan-Uul (18.9%), lead concentration in Nalaikh (8.3%), Bayanzurkh (5.4%), Chingeltei (3.3), mercury concentration in Baganuur ( 24.7%), Khan-Uul (18.4%), and chromium concentration in certain locations of Khan-Uul (4.7%) districts exceeded the standards, respectively. The concentration of soil cadmium (21.2%) and lead (7.7%) near the technical market, mercury concentration (26.3%) near the market and shopping center, and chromium concentration (58.9%) near the central treatment plant exceeded the maximum permissible levels. Conclusion Cadmium and mercury pollution were mainly detected in the heavy metal pollution of the soil of Ulaanbaatar city, and there is heavy metal pollution in certain locations of Baganuur and Khan-Uul districts. Heavy metal pollution is caused by activities such as technical markets, auto repair shops, markets, shopping centers, and treatment plants.