For maintaining of Zagros forests role in wild life, water and soil conservation, the suitable solutions and methods for assessing the existing conditions and planning for management of this forests should be given. To detection of suitable sampling method to study tree Diameter at Breath Height in the northern Zagros forest, Blake forest, in Baneeh region, Kurdistan province, and west of Iran was selected. 40 square sample plots one hectare (100×100 m) were selected and perfect inventoried. In every sample plot the position of tree, kind of species and Diameter at Breath Height (DBH) were recorded. In order to study of tree density (tree/ha) different sampling methods (rectangular sample with 20×50 m and 10×50, random sampling method with 40, 50 and 60 circle sample plots which everyone was 1000 m2) compered the prefect inventory. To determination of suitable sampling for study of tree Diameter at Breath Height (DBH) used the %E2 ×T indexes. To compere the Diameter at Breath Height (DBH) in the every sampling methods and perfect inventory used the t-test analysis. Data analyzing was done by SPSS16 software’s. Results showed that the rectangular sample with 20×50 m sample methods was the best methods and have maximum of accuracy. Overall results showed that the rectangular sample with 20×50 m sampling methods was (have minimum of time and %E2×T criteria) the suitable methods to study of density (tree/ha). Authors suggested to study of tree density (tree/ha) in the northern zagros forest used the rectangular sample with 20×50 m sampling methods.
