In recent decades, most of the businesses were started using electronic commerce. Today, B2B is the most popular model of electronic commerce. One of the issues in B2B systems is Participation. Participation means taking apart or gets involving for doing some tasks in a development process. However there are many studies on collaboration and communication in a B2B system, lack of study in participation is observed. A qualitative method based on interview, in a case study, was used for data collection. As a result, effective elements including centralized database, communication, accessibility, paperless work cycle and collaboration in a B2B system, can improve the participation significantly. 