The squeezing properties of atom laser are investigated with and without rotating-wave approximation by means of quantum theory in the system of optical field interacting with Bose-Einstein condensate of two-level atoms. The influences of the atomic eigenfrequency, the interaction intensity between optical field and atoms，the initial squeezing factor of optical field and the virtual photon field on the squeezing properties are discussed. The results show that two quadrature components of atom laser can be squeezed periodically. The quantum Rabi frequency and the collapse and revival frequency of atom laser fluctuation depend on the atomic eigenfrequency and the interaction intensity between optical field and atoms respectively. When the initial squeezing factor of optical field increases and the virtual photon field is considered, the degree of squeezing of the atom laser also increases.