On account of the hysteresis error of the sensor, a new kind of elasticity alloy suitable for a substrate material of the FBG sensor was studied. The elastic after effect and the elastic hysteresis effects of this alloy are very low. A new sensor structure was designed, using elastic steel and newly developed constant elasticity alloy as substrate materials and the two sensors’ pressure hysteresis errors were compared through pressure experiment. Experimental results show that the sensor in non-ferrous, made the process of pressure, and by using the new hysteresis error of pressure sensor material retardation is very small, for 0.099% error and can be neglected. Sensor has function of temperature compensation, can also measure of temperature and pressure. The sensor can be applied in oil tank, the temperature and pressure etc.