This article intends to study effective factors on Iranian gardens as similar atmosphere with meaning and environment values. First we try to study cultural roots of ancient Iran and its effect on elements and structure of Iranian gardens; in second chapter similarities among Islamic beliefs in Iranian gardens are studied. Then by accessing to a set of cultural-environmental criterions of Iran as an atmosphere that is binding to Iranian culture and beliefs and Iranian knowledge and techniques as a complementary factor is presented and finally Iranian gardens are presented as perfection and ideal work at its principles. Principles and criterions that are raised as a result of aforesaid factors have ever been developed during history of garden constructing in Iran have been maintained in spite of difference at material and main principles and criterions and surely it will be attention by architects.