The mud pump is among the important equipment for geological drilling. The article introduces the present situation of mud pumps equipped for deep core drilling and relationship between the parameters of flowrate, pressure and hole depth, with the focus on the mud pump design for 5000m intelligent geological drilling. The reasons to choose the final design are explained through comparison of various design alternatives with the main technical parameters and performance characteristics provided. In addition, the new technology and measures for dealing with the key technical difficulties on the design are present with some preview, which provides important theoretical basis for development of the mud pump.