Quality of service is defined as a comparison between customer expectations and service comprehension. Assessment and improvement of bus service quality is so important in order to increase the car ownership rate. In particular, research on the characteristics of service quality is important because of the high impact on customer satisfaction. Previous studies indicate that citizens have six indicators of travel time, convenience, accessibility, price, comfort, information, and safety are more important of other indicators. In this study, modeling of service quality indicators in the bus system of Zanjan city has been investigated. In this way, by these indicators, the most important factors of customer satisfaction were identified. The research method was empirical and the travelers were surveyed and the data extracted from the questionnaires were analyzed using the Smart PLS software. It is worth noting that at the end, a model was developed to determine customer satisfaction with the mentioned variables (quality indicators), which had the highest weights, respectively, safety, relaxation, travel time and convenience. In addition, the satisfaction of this system was 59%.