In order to make constant displacement pumps output multi-level constant flows and provide energy for several different pressure systems without a reducing valve, a double-stator multi-pump was successfully designed and tested, and the transmission theory was also presented. Taking the multi-pump and single-motor transmission system which consists of double-stator double-acting multi-pump and swash plate type axial piston motor for example, the influence of different volatilities of fluid output by multi-pump in different working ways on the motor output torque was analyzed. The results show that the effects of multi-pump on the system output characteristics were different in different working ways. When the inside pump and outside pump were working together, the motor output torque was superior to when they were working alone. When the fluctuation cycles of pump and motor were consistent, the motor output torque could be more stable by adjusting the lag angle reasonably. For verifying the correctness of the proposed theoretical analysis, the experimental platform of multi-pump and single-motor driving system was built, and the relevant data were collected to depict the diagram of uniformity coefficient of motor output torque in different working ways. The experimental result was consistent with the theoretical analysis, which showed the correctness of theoretical analysis.