Abstract: A liquid-filled passive color changeable sensor for bolt axial force is designed. In order to detect the axial force of the bolt, the characteristics of different colors of the sensor under different deformation of the sensitive material is used. ANSYS is used to carry out the fluid-solid coupling mechanical simulation of the whole feasibility and calculate the multi-node stress of the sensitive material section to analyze the color uniformity; the relationship tests of pressure and color are conducted for the sensor, and the influence degree of temperature difference and partial load is analyzed. The results show that the sensor can display different colors under different pressures, and the color is uniform, which is easy to observe; when the partial load distance is within 5 mm and the temperature difference is 0 to 20 ℃, the temperature difference and partial load have no effect on the color uniformity and the sensitivity of the sensor.