This research is a proof-of-concept of important functions and/or characteristics analytically and experimentally. The impact of the increasingly rapid development of technology and the internet has not only penetrated the trade industry, but also the Indonesian financial industry. This is marked by the presence of financial technology (fintech). Financial transactions through fintech include payments, investments, borrowing money, transfers, financial plans and comparisons of financial products. Digital financial services or financial technology (fintech) are carried out based on a legal basis. This follows after the issuance of the Financial Services Authority Regulation (POJK) Number 77/POJK.01/2016, concerning Information Technology-Based Money Lending Services (LPMUBTI). Indonesia faced a number of challenges during the covid -19 period, starting from changing habits, because one of the transmissions of covid was during payment transactions, giving cash had a big influence on the transmission of covid, therefore the government recommended making payments using other than cash. Therefore, this study aims to determine the effect of knowledge, security, convenience and trust on the behavior of the Financial Technology (Fintech) usage system, especially online-based payments, during the pre-pandemic and post-pandemic periods. by using multiple linear regression. This research was conducted in the DKI Jakarta area using a survey method. Researchers used SPSS software to test research data. The results obtained from this study are that there are differences in knowledge, safety, convenience and trust between before and after the Covid 19 pandemic