The invention belongs to the field of fluid machinery and particularly relates to an automatic control system for a drainage pumping station and a design method of the automatic control system. A pressure instrument control system is adopted to control the opening degree of an outlet valve of the pumping station; a valve control system is adopted to control the operation numbers of pumps of the pumping station; a parallel-connection pump set control system is adopted to control the operation conditions of other branch pumps; and a pump feedback control system is adopted to control the working state of the pressure instrument control system. Pumping station automation intelligent operation is achieved, all parts of the pumping station work in a coordinating and unifying mode, and it is guaranteed that the pumping station has good stability.