Nowadays, off-highway vehicles enjoyed a significant status in the national defense and civil construction. There is no doubt that the working conditions of off-highways are quite different from the conventional passenger cars, hence, their suspensions are particularly designed. Since the hydro-pneumatic suspension technology is maturely applied in engineering machinery, this paper presents a concept for a novel energy-harvesting device, which is applied in off-highway vehicles based on hydro-pneumatic suspension, namely, electro-hydraulic energy-harvesting suspension (EHEHS). The EHEHS took the fundamental of mechanism-electronic-hydraulic system, which consisted the following elements: a cylinder, 2 check valves, a hydro-pneumatic spring, a hydraulic motor, a DC motor, a processing circuit and a battery. In the EHEHS system, the cylinder is used to transmit the vibration energy into hydraulic energy, which is stored in hydro-pneumatic spring. The hydraulic motor is the energy conversion device that could translate the hydraulic energy into rotational kinetic energy, which could be converted into electric energy by the electric motor. The final electric energy is conserved in the battery after treatment by the processing circuit. Apart from the description of the configuration of the EHEHS, this paper also discuss the stiffness and damper characteristic of the novel energy-harvesting suspension by mathematic derivation, and a simulation based evaluation is present to show its application in an off-high way commercial vehicle.