The corporate income tax is one of the important taxes in tax system of the countries. Its burden is different between developed countries and developing countries. In Vietnam, the corporate income tax is a most important tax and its contribution to the state budget is higher than other taxes. The purpose of this article is to analyze the determinants of corporate income tax burden in Vietnam. Through the descriptive statistics method, the findings show that the corporate income tax burden is the highest in all of Vietnam's taxes, about 10% per year during the period of 1999 - 2012. Through the empirical method, the author finds that there are three quantitative factors and one qualitative factor affecting the burden of Vietnam's corporate income tax, includes revenue from corporate income tax, GDP at current prices, tax rate and time trend.