Purpose: There is increasing interest in the trends and requirements associated with improvement in the competition of commercial banks. Many studies have been conducted on this topic in Vietnam as well as in the rest of the world. In the present study, the factors affecting the level of competition in the banking system in Vietnam have been studied. Design/Methodology/Approach: We employ the Bayesian Multilevel Generalized Linear Model to identify the factors affecting the level of competition in the banking system in Vietnam. Findings: The findings show that the eight variables that affect the level of competition in Vietnam commercial banks were identified, including previous-year competition, equity on total assets ratio, loans on total assets ratio, operating expense on the operating income ratio, return on equity, bank size, economic growth, and inflation rate. Moreover, the results demonstrated that during the 2008-2009 crisis, there was a positive relationship between the crisis and the Lerner index. Practical Implications: Based on the research results, we provide policy implications to improve the competitive status of commercial banks in Vietnam. Originality/Value: The results of the present study would serve as a basis for assisting the policy-makers and the other stakeholders to better understand the current state of bank competition and the factors affecting the level of bank competition, which would assist them in formulating strategies and solutions to improve bank competition in Vietnam.