An intuitive eco-driving assistance system is mounted on a vehicle and has an input module, a control module and an output module. The control module is electrically connected to the input module and the output module. The output module acquires images ahead of the vehicle and speed signals for the control module to recognize a speed limit, traffic lights and a speed and distance of any obstacle on the images. Furthermore, according to the driving limits of the road and actual vehicle speed, the output module prompts for an eco-driving instruction and the speed limit meeting the road condition visually or audibly. Accordingly, the issue of conventional vehicles being structurally complicated and costly for conserving energy, only passively prompting fuel consumption, and consuming more fuel can be solved without requiring any additional and complicated system.