Abstract: A new type of color changeable sensor without power supply for monitoring axial force of rock bolt is designed. According to the linear relationship between the axial force of rock bolt and the inner pressure of the system, the opening and closing of the valves are driven by the inner pressure, and the combination of the colored liquid in the accumulator will cause a changed color to ensure the real-time monitoring of the bolt. Four colors will appear respectively when the axial force of rock bolt is changed from 0 to 240 kN through the simulation of the AMESim, the experiment shows that the color can be easily perceived and the sensor is feasible and effective.