The basic aim of this study is to identify geo mechanical parameters of rock mass of Jam Shir dam site in the Gachsaran in Kahkoulooie and Bouyerahmad province. Utilizing water resources of Zohreh river is main goal of constructing of mentioned dam to supply 110 thousands hectare of agricultural area of south of Iran and to supply necessity electricity of adjacent regions. Jam Shir dame with approximately 140 meters height and 1,700,000,000 cubic meters volume is created as roller weighted concrete dam. During accomplishing engineering projects, in addition to descriptive and qualitative information that was gathered using field investigation and underground exploration, quantitative data for intrinsic characteristics of materials is needed. Hence, the rock in the area under in-situ situation is tested in the laboratory. The goal of these examinations is to identify and left; MARGIN: 0cm 0cm 0pt; unicode-bidi: embed; DIRECTION: ltr" align=left