In today’s financial industry, Fintech (financial technology) has showed its role of an innovation-driving area, which can bring outstanding changes to the traditional financial market. This article will briefly introduce Fintech as well as its development in Vietnam. Besides, the research also provided a survey on experts’ opinions on the challenges to the promotion of Fintech application for the modernization of the banking-finance system in Vietnam. The survey results of 40 experts in banking with knowledge of Fintech identify five challenges faced by Fintech companies in Vietnam: (1) legal corridor; (2) infrastructure; (3) Fintech companies; (4) customers; and (5) human resources. From these five challenges/barriers, there are 14 detailed aspects. The results of the expert survey using descriptive statistics show that all five factors are assessed to be low and need to be better addressed in the future. The authors suggest several solutions for further development of Fintech to support the modernization of the banking-finance system in Vietnam: (1) quickly complete the regulatory framework; (2) introduce policies on tax exemption; (3) promote research and application of the benefits of block-chain technology; (4) utilize the abilities of the human resources; and (5) actively promote and popularize knowledge about Fintech.