Using the FeGa magnetostrictive film as the sensitive material, a surface acoustic wave (SAW) current sensor with high sensitivity is designed and optimized. It is fabricated by using a SAW delay line with a center frequency of 150 MHz as the sensing element, and the FeGa thin film is deposited on the surface of the SAW propagation path of the delay line using radio frequency (RF) magnetically controlled sputtering method. The developed sensor is connected to an oscillation circuit composed of an amplifier and a mixer, and the output signal is used as a sensing signal by making a difference with the uncoated reference device. Under the action of the electromagnetic field, the magnetostrictive effect produced by the FeGa film causes a change in the propagation velocity of the SAW, and finally the applied current is evaluated with the corresponding differential oscillation frequency offset. In order to further improve the performance of the sensor, the optimized preparation conditions are determined by controlling the preparation processes such as different sputtering power and annealing heat treatment. The experimental results show that when the FeGa film thickness is 500 nm, sputtering power is 100 W, and annealing temperature is 300 ℃, the current sensor has good linearity, repeatability and high sensitivity (up to 24.67 kHz/A).