There are usually hardening and thermal mismatch in traditional adhesive sealing FBG under the ultralow temperature environment. In order to solve the problem,a metallic packaging FBG temperature sensor was proposed,and FBG was packaged and fixed on the surface of special aluminium alloy by ultrasonic welding technique. The ultralow temperature sensing properties of two packaged FBG sensors were tested in temperature range of -160 ~ 0°C. The results indicate that the metallic-packaging FBG sensors have good linearity and the correlation coefficient of more than 0.99. The temperature sensitivity coefficients of stretching-packaging and compress-packaging FBG sensors are 27.88 pm / ℃ and 26.17 pm / °C,respectively,which are 2.75 times and 2.58 times as much as that of the bare FBG. The metallic-packaging FBG temperature sensor has excellent ultralow temperature response characteristics.