Abstract: Our article introduces a method to construct the squeeze operator in quantum field theory: consider two free Hamiltonians for the same scalar field with two different masses, through Bogoliubov transformation, we derive a generalized squeeze operator which maps the ground state of one to the other. The efficiency of its operation is verified in both the Dirac representation and also the Schrodinger wavefunctional representation in quantum field theory. We believe that the squeeze operators can be found similarly in any real scalar field theory as long as there are two sets of creation and annihilation operators connected by linear transformations.