This pre-registered report aims to explore the impact of cultural diversity on fintech development through the perspective of dialectal diversity. Specifically, we want to investigate three key questions: (1) Does cultural diversity influence fintech development? (2) If it does, what are the underlying mechanisms? (3) Moreover, does the impact of cultural diversity on fintech development vary across regions or households with heterogeneous characteristics? To explore these questions, we plan to utilize regional dialect data and analytical methods such as instrumental variables and fixed effects to examine fintech adoption at the household level. This report contributes to understanding the informal institutional factors underpinning the development of fintech, and provides new theoretical and practical perspectives for building a more comprehensive and inclusive fintech system.