In order to reasonably allocate the acid fluid volume for staged acidizing in a horizontal well for heterogeneous carbonate reservoir，it is crucial to fully consider the permeability heterogeneity along the wellbore and to accurately evaluate the damage radius and damage permeability of each segment. Based on the Darcy’s law，a model of damage radius was deduced with consideration of drilling bottom-hole pressure difference，soak period of drilling mud and permeability distribution. Based on reservoir-wellbore coupling model and tested inflow profile，a new approach of calculating damage permeability distribution was proposed. The process of acid fluid volume optimization for heterogeneous carbonate reservoir was illustrated by a case study on real well data. Since the influence of the permeability heterogeneity and the real production data is fully considered，the proposed design procedure can improve the reasonability of acid fluid volume allocation along the horizontal well，remove the formation pollution effectively and restore oil well productivity compared to the traditional non-specific acid allocation pattern which is based on the elliptic cone damage zone model.