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The distribution of water resources and the application of seawater desalination pumps in China were analyzed. Based on the traditional water pump, a water pump named two-dimensional cartridge pump composed of some pairs of unit pumps was proposed. Depending on the basic components of the unit pump set, namely the combined characteristics of two unit pumps were studied. Through the theoretical analysis and comparison with the traditional axial piston pump and centrifugal pump for water, the working principle and potential advantages of the two-dimensional cartridge water pump were expounded. The advantages included structural force balance, large displacement, oil and water separation, no structural flow ripple and so on. In the meantime, the mathematical modeling and analysis of the contact surface between cam and roller were carried out. Being different from the method of obtaining contact points by taking points in two dimensions after compensation, the mathematical model of contacting surface was established based on the analysis of the spatial contacting relationship between the roller and cam. The mathematical model of contacting surface was more precise which offered theoretical basis for the further research. The correctness of the mathematical model of contact surface and the advantage of no structural flow pulsation in two-dimensional cartridge pump were verified by the experimental study of piston movement and flow characteristics of two unit pump set.