Positive psychology is a subcategory of psychology which emphasizes on the importance of happiness on human’s health, using personal and social facilities. This field has different categories which are able to prosper human’s health both physically and mentally. In addition, by having a look at rich and ancient literature of Iran, we notice that there are some pieces of work which include moral and educational messages which also aim to increase human’s physical and mental health. So, in this study, we have tried to find different categories of positive psychology in Gulistan book, one of the most significant literary works written by one of the most well-known poets and writers of ancient Iran. This is a descriptive project and the content of Gulestan has been investigated. The book has been used as the society and sample, then the tales and poems, which include positive psychology factors, have been explained. The result of the project indicates that the positive psychology categories like happiness, optimism, emotional intelligence and sense and creativity are the categories which are used in Sadi’s Gulistan.