This paper aims to identify key determinants impacting on a firm performance of Small and Medium-sized Enterprises (SMEs) in Viet Nam. SMEs have contributed significantly to the overall Vietnamese economy. However, in the context of emerging market in Viet Nam nowadays, SMEs have to deal with a tough competitive market. Hence, an awareness what factors enhancing firm performance enables them to achieve sustainable development. Based on the survey of 2551 Viet Nam SMEs, which was conducted by Science & Social Association, Viet Nam Ministry of Labor-Invalids and Social Affairs, the paper provides the holistic view of several perspectives' impacts on the performance of SMEs. We find out that three main factors, including human resource, education level of entrepreneurs and training cost have significant effects on the performance. As considering in the field of international trade, the results illustrate the more SMEs conduct export activities, the better enterprises' performance. Specifically, we point out that other factors such as formalization, credit access, informal loan and firm location are strongly associated with the performance. Furthermore, we also conducted in-depth interviews with 6 entrepreneurs and top managers to explore current challenges of Vietnamese SMEs and suggest appropriate solutions to overcome them.