Static ice pressure of the ice freezing and thawing as the primary control load poses a serious threat to the hydraulic structures. A special sensor is required because of its harsh testing environment. A novel pressure sensor based on the fiber Bragg grating with square diaphragm is proposed for static ice pressure detection. The finite element analysis method is utilized to simulate and analyze the sensing structure, static analysis, and transient analysis for the proposed sensor. The static ice pressure sensing system is established to investigate the performances of the proposed sensor. Experimental results demonstrate that the pressure sensitivity of the sensor is 1.89 pm/kPa within the range of 100–500 kPa, with a linear record of 99.15 %. Moreover, the sensor has low hysteresis and good repeatability. The relative error of the sensor caused by temperature is 0.90 %, which indicates that the influence of temperature on pressure measurement can be effectively eliminated. Meanwhile, the proposed sensor is used to detect the dynamic variations of the static ice pressure during continuous processes of freezing and thawing. The researches indicate that the designed pressure sensor is simple and economical which is suitable for static ice pressure detection.