Hydraulic excavator driven by an internal-combustion engine is widely used in the construction field. As engine often works in inefficient area, some problems, such as high pollutant emissions, noise and low efficiency exist universally. In order to improve energy efficiency and reduce the emissions, applying hydraulic power source driven by electric motor to hydraulic excavator has become an important research direction. A power source was presented with variable speed induction motor to drive variable displacement pump, which used the fast response characteristic of variable displacement pump to make up for the slow dynamic response of variable speed induction motor, and it was applied to excavator. In order to fully understand the characteristics of the designed electro-hydraulic power source and provide a reference for electric hydraulic excavator design, the dynamic, static and disturbance characteristics of electro-hydraulic power source were studied from both the perspectives of theory and experiment. Then, load disturbance test and arm lifting test were completed on the test rig under the same working conditions. Compared with the characteristics of traditional engine used to drive hydraulic power source system, the new variable speed-variable displacement power source reduced the rotation speed fluctuation by 23.5% in the load disturbance test, the rising time of pump output pressure and flow was reduced by 14.9% and 26.3% in the arm lifting process. The new electro-hydraulic power source owed better characteristics.