We present a method to prepare a squeezed atom laser via stimulated Raman transition of the Λ-type three-levels atoms in sodium atom Bose-Einstein condensate (BEC) interacting with two light beams,a weaker squeezed coherent probe light and a stronger classical coupling light,and investigate the squeezing properties of this atom laser. The results show that the quantum fluctuation of this atom laser can be periodically squeezed. The squeezing depth of such atom laser is determined by the initial squeezing factor of the probe light,and the squeezing period of that is related to the mean number of atoms in trap,the strength of interaction between squeezed light and BEC atoms,and the detuning of the light.