The knowledge about spatial variation of stress field is an important step in the identification of geodynamic and seismotectonic characteristics. Inversion of focal mechanism solutions is one of the most common methods for determination of stress field and the shape ratio in a tectonic region. In this paper, Iterative Joint Inversion method is used to determine principal stress axes from earthquake focal mechanisms in the Zagros continental collision zone of Iran. In order to determine the influence of dependent events on the inversion results, the declustering process is carried out by the Urhammer's method. The area is divided into seven subzones according to the stress field heterogeneity in the Zagros region. In each subzone, the trends of principal stress axes, the orientation of maximum horizontal stress, stress regime and the shape ratio are determined. The results show that the compressional stress direction averages NNE-SSW that accord with the current convergence between the Arabian plate and Iranian micro-continent. A gradual counterclockwise rotation of the compressional axis is also concluded which is compatible with spatial changes in the Arabian–Eurasian convergence paths along the Zagros. The stress regime of most of the subzones is deduced as the Transpression that reflects oblique convergence. The orientation of the maximum principal stress (${\sigma }_1$) show the lowest uncertainty in respect to the intermediate (${\sigma }_2$) and minimum (${\sigma }_3$) principal stress axes. The shape ratio error in all zones are less than 6 and 7.2 percent before and after implementing exclusion respectively, which indicate this error increases with removing the dependent events in all zones except for zone 3.

有关应力场空间变化的知识是确定地球动力学和地震构造特征的重要步骤。震源机制解的反演是确定构造区域应力场和形状比的最常用方法之一。本文采用迭代联合反演方法从伊朗扎格罗斯大陆碰撞带的地震震源机制确定主应力轴。为了确定相关事件对反演结果的影响，采用Urhammer方法进行了解聚过程。根据Zagros地区的应力场异质性将该区域分为七个子区域。在每个分区中，主应力轴的趋势，最大水平应力的方向，确定应力状态和形状比。结果表明，压应力方向平均为NNE-SSW，与阿拉伯板块和伊朗微大陆之间的当前收敛一致。还得出了压缩轴逐渐逆时针旋转的趋势，这与沿Zagros的阿拉伯-欧亚收敛路径中的空间变化兼容。大多数分区的应力状态被推导为反映斜向收敛的Transpression。最大主应力的方向（还得出了压缩轴逐渐逆时针旋转的趋势，这与沿Zagros的阿拉伯-欧亚收敛路径中的空间变化兼容。大多数分区的应力状态被推导为反映斜向收敛的Transpression。最大主应力的方向（还得出了压缩轴逐渐逆时针旋转的趋势，这与沿Zagros的阿拉伯-欧亚收敛路径中的空间变化兼容。大多数分区的应力状态被推导为反映斜向收敛的Transpression。最大主应力的方向（${\sigma }_{\mathrm{1个}}$）相对于中间体（${\sigma }_2$）和最小值（${\sigma }_3$）主应力轴。在实施排除之前和之后，所有区域中的形状比率误差分别小于6％和7.2％，这表明该误差随着除去区域3中所有区域中的相关事件而增加。