The construction shield section for the new rail transit line of Hefei metro requires to apply to the shield segment outer diameter of 6 200 mm. In order to meet the requirement, an EPB shield with the shield tunnel segment outer diameter of 6 000 mm is studied. First, an expansion modification scheme for composite cutterhead of shiled machine is proposed, the excavation diameter of which is modified from 6 280 mm to 6 470 mm. Then, on the basis of analyzing and calculating the force composition of shield cutterhead, a 3D model is established by using Solidworks. Last, the modified cutterhead is validated by ANSYS software for static and modal analysis, the results show that the modified composite cutterhead meets the requirements of strength and stiffness. At present, the cutterhead of the shield machine has completed the modification design in the factory and arrived at the project, and will be practically applied in the construction of Hefei metro.