Embodiments of present invention include a method and apparatus of estimating power supply of a 3D IC. The method particularly includes obtaining current information and layout information of circuit modules contained in a specific region of the 3D IC, gridding the specific region so as to form at least one three-dimensional grid having a plurality of side edges along chip stacking direction of the 3D IC, determining current of at least one of the plurality of side edges based on the current information and layout information of the circuit modules, and estimating power supply of the 3D IC based on the current of the at least one side edge. With the method and apparatus embodiments of the invention, power supply of a 3D IC may be effectively estimated and analyzed.