Abstract：A new pseudo three-dimensional analytic solution for stresses of horizontal borewell in transverse isotropic rock considering the hydrostatic pressure of borehole，the maximum and minimum horizontal principal in-situ stresses and the overburden stress was established based on the anisotropic linear elastic mechanics，coordinate transformation methods and the superposition principle. The distributions of three principal stresses of the horizontal borewells in shale and sandstone were analyzed. The results show that compared with the situation in mechanically isotropic formations，the anisotropy of rock mechanical properties does not affect the principal stress ，but affects the distribution of the principal stresses and . The greater the anisotropy is，the more affected the principal stress and . High mechanical anisotropy may increase the number of tensile broken points on borehole wall.