ing at the issue of strain of elastic packaging materials for fiber Bragg grating (FBG) sensors used in high-temperature oil and gas wells in a wide temperature range, austenitic stainless steel and trial-produced niobium-based constant-elastic alloys are designed and manufactured into elastic strain elements, and the FBGs are pasted on them for packaging to make tension sensors respectively. The strain sensing performance of the two materials at 30--250 ℃ is investigated and compared by applying tension to the sensors at different temperatures. The results show that linearity of the tensile response of the two alloy materials at different temperatures is better than 0.999; however, as temperature increases, the tensile response sensitivity decreases, repeatability decreases, and hysteresis increases. Temperature affects the strain sensing performance of the elastic material; in the temperature range of 30--250 ℃, the sensor packaged using the trial-produced niobium-based constant-elastic alloy is superior than the sensor packaged using the austenitic stainless steel material in terms of repeatability, hysteresis, linearity, and sensitivity stability. Thus, the trail-produced niobium-based constant-elastic alloy can be used as an elastic packaging material for FBG sensors in a wide temperature range.