The study aims to substantiate and analyze the criteria for assessing the quality system of design organizations applying a modular approach. The modular approach allows assessing various aspects of the design organization's activities by dividing them into separate modules according to the organizational and technical model of functioning. Quantitative indicators of the criteria are based on the expert method and the data of the operational activities of the organization. The importance of the criteria is determined by the method of hierarchical analysis (AHP) within each module. The obtained weights of the factors allow ranking both single indicators and complex indicators for each module and integral by the degree of significance. This enables assigning corrective actions to improve problem areas in the project organization's performance. The systematized list of criteria provides a basis for determining private and general indicators of the quality system, which can be used to determine the type of organization, justify its rating and identify the risks of design work. The areas of design activities are recommended according to the rating and the type of organization. This ensures transparency of information for example, in the system of self-regulation, effective competition and contributes to improving the quality of project documentation.