An electric motor-pump prototype with compact structure has been developed, and a testing system for the prototype has been established to obtain testing data, such as noise, efficiency, and rotational speed. Compared with the performance of the electric-hydraulic power unit, the noise level of the prototype maximally decreases by 13.4dB, the volumetric efficiency is nearly 1.3% higher during the delivery pressure rising from 0MPa to 15MPa. However, the total efficiency of the prototype is 4.9% lower due to the lower rotational speed and the oil-immersed loss. Aiming at the noise abatement and the decline in efficiency, CFD and Ansoft are used to analyze the suction flow field of main pump and the rotational speed, and then the key factors that impact on noise and efficiency of the prototype are presented. The research results show that adopting the charging effect measure, setting a centrifugal charging pump at the inlet of the main pump, can prevent the cavitation noise caused by insufficient oil suction of the main pump. And the electrical resistance of the squirrel-cage rotor has a great impact on the rotational speed and further impacts on the efficiency. Finally, an improved virtual prototype with improved rotor is presented to increase the total efficiency by 2.4%.