This paper aims to design a tunnel road energy harvesting system, which is applied in the occasions around road tunnels such as the decelerating zones in front of road tunnels or downhill. This paper proposes design, modeling and simulation of a novel hydraulic road tunnel energy harvesting system for the purpose of harvesting energy from the road vehicle flows. The main improvement is the novel design of the mechanisms of capturing and storing energy through hydraulic principle and translating the two-way vertical movement of speed bump into one-direction rotation of DC motor. The simulating results proved its validity of proposed energy harvesting system with a high efficiency of 67.6%.