Abstract: In view of the lack of orthotropic in-situ stress prediction methods, this article first constructs the conversion relationship between anisotropic dynamic and static rock mechanical parameters; secondly, based on the relationship between effective stress and strain, the general solution form of Biot coefficient is derived, and the specific solution of Biot coefficient under different conditions is given; then, starting from the generalized Hooke's law of anisotropy, the complete analytical expression of the orthotropic in-situ stress of the stratum with respect to the elastic parameters of the rock is derived; finally, taking Well x1 as an example for practical application, the accuracy of the ORT in-situ stress calculation model is verified. Through the research in this paper, the following conclusions are mainly drawn: the horizontal and vertical rock elastic parameters of shale formation have significant differences, and establishing corresponding dynamic and static conversion models according to direction is beneficial to improving the conversion accuracy of static rock mechanics parameters; in the direction perpendicular to the bedding plane, Biot coefficient α₁₁ is significantly smaller than α₃₃, and the average relative difference reaches 13.4%; in the direction parallel to the bedding plane, the difference between Biot coefficients α₁₁ and α₂₂ is relatively small; the anisotropy characteristics of Biot coefficients cannot be ignored, and this factor must be fully considered when calculating the in-situ stress. Comparing the errors between the prediction results of various models for horizontal principal stress and the measured data, it is found that the ORT model has the highest accuracy, followed by the VTI model, while the ISO model has relatively low prediction accuracy. This study can provide basic data and guidance for wellbore stability analysis and fracturing segment optimization design.