This study is conducted to investigate the impact levels of determinants influencing audit quality of ODA projects with the case of State Audit of Vietnam. By interviewing state auditors, observing audit activities in the audit process of ODA projects and sending questionnaires to auditors, primary data were used for running the regression model of audit quality. The results show that two groups of external factors of legal framework and auditee have positive relationships with audit quality, but auditee has a stronger impact. For internal determinants, the impact levels to audit quality reduce from expertise to duration, knowledge, profession with a significant level of 1%. Compliance variable has the lowest level of influence with 10% of a significant level. Working conditions and control are not statistically significant and no impact on the audit quality of ODA project. Based the findings, some recommendations are given for State Audit of Vietnam to improve audit quality of ODA projects.