Butler productivity formula for steam assisted gravity drainage （SAGD） assumes that the reservoir is homogeneous and isotropic, without considering the impact of the vertical permeability, which causes that the SAGD production capacity result is higher than the actual value. This paper compared the correction methods of productivity formula for conventional horizontal well in anisotropy reservoir, and carried out the average permeability correction of SAGD productivity formula by using nonlinear regression fitting. The SAGD numerical simulation result was applied to push back the value of the average permeability in the analytical formula, in order to establish the corresponding relations among the average permeability, horizontal permeability and vertical permeability, and finally obtain the expression of permeability in anisotropy reservoir through the regression. The application result shows that the calculation result of the corrected SAGD productivity formula is closer to the true value.