This paper analyzes and summarizes the current situation of Mongolia’s foreign trade，studies its impact on the country’s economic development，and finds out the practical difficulties and challenges. The paper studies the impact of trade with China and Russia on the economic development of Mongolia by evaluating the geographical location and product structure of import and export. This paper also analyzed the foreign investment in Mongolia，clarified the status of China and Russia among foreign investors，analyzed the reasons why there are many Chinese investment companies，summarized the tendency of foreign investment in mineral industry，found out the reasons for the small inflow of foreign investment into the Mongolian economy and put forward the suggestion to solve the problem.