E-government initiatives have been carried out around the world, which offer wide chances to deliver the variety of services more efficiently to their citizens. The success of such e-government services relies on both government support and users’ adoption. This study chooses the UTAUT(Unified Theory of Acceptance and Use of Technology) model and modified the initial UTAUT model by including data security and legal environment to explore factors influencing the e-government adoption in Mongolia. Data were collected from 104　respondents who were interested in Mongolia’s e-Government.　The research results show that the e-government adoption in Mongolia is affected by effort expectancy, facilitation conditions, legal environment, data security, and behavioral intention. Nevertheless, performance expectancy was not significant on behavioral intention. This study provides suggestions for policy makers in order to improve e-government adoption.