The present study tends to investigate the relation between the complexity and semantic distance of Icons and their Effectiveness in searching module of Simorgh, Azarakhsh and Nika applications. Following a correlational survey, the participants of this research consisted of two groups: specialists and end-users. The former consisted of 30 PhD in Knowledge and Information Science, and the latter included undergraduate students of Shiraz University. First, the effective and non-effective icons were identified by end-users. Then, their complexity and semantic distance was investigated by specialists. The results of the study showed that there was a statistically significant difference between effective and non-effective icons; effective icons have less complexity and semantic distance than non-effective icons. Furthermore, it showed a significant strong relationship between the complexity of icons and their semantic distance. The more complexity, the more semantic distance it was, and vice versa. Despite the importance of the studies on the relation between the complexity and semantic distance of icons and their effectiveness, little attention is paid to it in the area of digital library applications. Investigating the studies on the relation between the complexity and semantic distance of icons and their effectiveness may clarify effective icons’ features. It also helps designers to design effective icons and build better and easier interaction between users and digital library application.