A series of Gd3Al2-xGax alloys over a composition range (x=0,0.1,0.3,0.5) were prepared from high purity Gd, Al, and Ga by arc melting under purified argon atmosphere on a water-cooled copper crucible, then annealed in vacuum at 1073 or 1173K for 36h. The X-ray diffraction pattern indicated that these alloys were single phase of Zr3Al2-type structure. Magnetization isotherms at different tempertures of these alloys were measured between 180 and 300K under the magnetic field up to 1.12106A/m using vibrating sample magnetometer. We found that magnetic entropy change of Gd3Al2-xGax(x=0.1,0.3,0.5) was larger than that of Gd3Al2, and the s of change (about 3.0J/kgK) of Gd3Al2-xGax(x=0.1) was observed at 280K under a magnetic field of 1.12106A/m.