The aim of this study is to measure the efficiency of Vietnamese universities and the effect of environmental factors on the efficiency of the universities. We used data enveloping analysis (DEA) to evaluate the efficiency of thirty seven universities in Vietnam for the period from the academic year of 2013-2014 to that of 2017-2018. Four inputs (the number of academic staffs, the number of student, campus area for training and capital) and three outputs (the ranking of universities in Vietnam of Webometrics, the world ranking of universities of Webometrics, the percentage of graduates) in efficiency analysis were used to measure the efficiency of Vietnamese universities. At the same time, we also investigated the effect of input, output and environmental factors on the efficiency scores of the universities by applying the linear regression model OLS (ordinary least square). The findings show that public universities have had lower efficiency than private universities. We also found that the number of students have negatively associated with the efficiency scores of universities, while the percentage of graduates and ranking of universities have the positive effects on those. Some implications are provided to improve universities’ efficiency.