Abstarct: The present study aims to investigate the impact of financial technologies (FinTech) on the trading volume and liquidity of the Iranian capital market through the mediation of retail traders' behavior. This study is applied in terms of purpose and descxriptive-correlational in terms of method. The statistical population of the study consists of retail investors active in the Iranian Stock Exchange, of which 410 questionnaires were distributed in the first half of 1405 and 395 people were selected as a sample. The data collection tool was a questionnaire, and content validity and convergent validity were used to measure its validity, and the results showed that the research items have the necessary validity. Also, the reliability of the research tool was examined using Cronbach's alpha and composite reliability, and the values obtained were desirable and indicated the stability and appropriate internal consistency of the measurement tool. Data analysis was performed using structural equation modeling and SmartPLS3 software. In this study, financial technologies were considered as independent variables, trading volume and market liquidity as dependent variables, and retail trader behavior as a mediating variable. The findings of the study showed that financial technologies have a positive and significant effect on trading volume in the capital market with a coefficient of (0.278). Also, financial technologies have a positive and significant effect on capital market liquidity with a coefficient of (0.307). The behavior of retail traders also has a coefficient of (0.385) on capital market liquidity, and the behavior of retail traders has increased trading volume with a coefficient of (0.523), and the existence of financial technologies has a significant and positive effect on retail trader behavior in the capital market with a coefficient of (0.669). In addition, the results indicate that the behavior of retail traders plays a significant mediating role in the relationship between financial technologies and trading volume. Also, the behavior of retail traders has a significant mediating role in the impact of financial technologies on market liquidity. The results of this study indicate that the development and application of financial technologies can increase trading volume and improve the liquidity of the Iranian capital market by improving the trading behavior of retail investors. Accordingly, more attention from policymakers, financial institutions, and capital market activists to the development of fintech infrastructure and the management of retail investor behavior can be effective in improving the efficiency and dynamism of the Iranian capital market.