The Sn-Al alloy of about 350 ℃ melting point was manufactured,and the fiber Bragg grating(FBG) sensor coated with nickel(Ni) plate was casted into the Sn-Al alloy.This method can improve the welting performance between the FBG sensor and the mental structure and enhance the mental structural materials’ sensitivity.The temperature sensing tests indicate that the FBG sensor can transmit signals normally after it has been casted with Sn-Al alloy under the melting temperature of 350 ℃,and the temperature sensitivity of FBG has increased from 10.8 pm/℃ to 17.3 pm/℃ during warming process and to 17.4 pm/℃ during cooling process.