Due to the fact that customer expectations are constantly increasing, organizations are required to go beyond the basic needs of customers, meet customer expectations, and shift their focus from merely satisfying customer needs to building loyalty and trust by creating long-term relationships. , mutual and profitable (quality of communication) for both parties. With the understanding they have gained of the importance of customer satisfaction, organizations are gradually moving away from traditional marketing and tending towards relational marketing. ; Therefore, the purpose of this research was to formulate and validate the relational marketing model in the banking industry of Iran with the approach of building trust and building customer loyalty with a mixed approach. Quantitative) has been analyzed. In the first stage, qualitative method and in-depth interviews were used to identify the components of the model. In the qualitative part, there are 15 university experts who were selected in a targeted way. In order to analyze the data of the qualitative part, the theme analysis method was used using MaxQuda software. Next, in order to fit the model designed in the qualitative part, a quantitative method with a structural equation modeling approach was used. The participants in this section included 384 customers of Bank Mellat in Hormozgan province, who were selected using the available probability method. The tool of data collection in the quantitative section was a questionnaire based on the findings of the qualitative section, whose validity and reliability were confirmed. Quantitative part data analysis was done by pls4 software. The results of the qualitative part showed that 15 interviews, including 7 main categories and 16 subcategories and 60 codes, were identified for developing the relational marketing model. In the quantitative section, it was found that there is a significant relationship between relational marketing and its factors, and the designed model has an acceptable fit. Relationship marketing is an old idea with a new approach. Because of the significant benefits of relationship marketing, companies are moving towards choosing relational interactions over isolated interactions. Individual interactions are formed in the short term and relational interactions are formed in the long term. Relational interactions are preferred to isolated and short-term relationships due to the increased competitiveness of companies. Relationship marketing largely depends on the customer's attitude towards the service organization, commitment and performance and communication of the employees.