Abstarct: This study aimed to evaluate Paleo and neo stress regimes on the basis of earthquake focal mechanism solutions, and fault slip data in the eastern Sabalan mountain side, north-west Iran. both data groups Inversed by Right Dihedron method. Data was separated on the basis of P and T axes analyses. Focal mechanisms were used to determine the stress field using inverse and averaging technique. Principal stress focal mechanism data were determined by average of axes P&T and inverse method .On the basis of average of axes P&T, orientations of σ1, σ2 and σ3 stresses for Western Caspian basin have been determined to be 266/53, 300/10, 080/39 and in the eastern part of Azerbaijan block to be 030/06, 120/10, 290/80 respectively. On the basis of inverse tensor and by using region focal mechanisms of earthquakes, the orientations of σ1, σ2 and σ3 stresses in northwest of Western Caspian basin have determined to be 049/24, 316/06 and 214, 65 and the shape of the stress ellipsoid was determined to be 0.47, and in the eastern part of Azerbaijan block have determined as be 149/06, 250/64, 056/26 and the shape of the stress ellipsoid was determined to be 0.69. Finally, results of the two methods of averaging and inversion of slip data were compared which are almost identical. The results of fault slip analysis on the basis 221 fault slip surface in 7 units shows three stress phases from Eocene to Quaternary time. The results indicate that after Eocene time the tension stress axis had north west-south east direction, shows strike-slip stress regime whit 057/05, 314/68 and 149/22 orientation for σ1, σ2, σ3 respectively and stress ration of 0.38. The second stress filed is related to after Pliocene shows Compressional stress regime whit 032/00, 122/31 and 302/59 orientation for σ1, σ2 , σ3 respectively and stress ration of 0.45 for before Pliocene with Tensional stress axis in this filed have a north west- south eastern orientation, the orientations of σ1, σ2 and σ3 stresses in have determined to be 038/05, 273/82 and 128,07 the shape of the stress ellipsoid was determined to be 0.61. The results of Analysis of focal mechanisms data and fault slip are almost identical.