Fe-Ga alloys have important application prospects in high-tech fields， such as sensors, transducers and actuators due to their large magnetostriction under low saturation magnetic field and good mechanical properties. Although the microstructure mechanisms are still controversial for the extraordinary magnetostriction enhancement induced by nonmagnetic Ga solution into body-centeredcubic Fe, considerable experiments have indicated that the large magnetostriction of Fe-Ga alloys is closely related to the modulus softening behavior. Considering that modulus softening is a common feature of martensitic transformation in ferroelastics, researchers then suggested that Fe-Ga alloys may also have martensitic transformation phenomena. In order to deepen the understanding of large magnetostriction in Fe-Ga alloys, here we present a brief review on the modulus softening, martensitic transformation behavior as well as the correlation between martensitic transformation and magnetostriction of Fe-Ga alloys with Ga content between 21at.% and 27at.%.