The evolution properties of the amplit ude-square squeezing of the field in the system of single-mode light field int eracting with the nonlinear Jaynes-Cummings (J-C) model via two-photon proces s are studied by means of quantum theory.The influences of the nonlinear correct ion term,the two-photon frequency detuning and the thermal noise on the squeez ing degree of the amplitude-square squeezing of the field are discussed. -