A new statistical model for infrared image is presented, which combined Gauss-pdf and generalized Gamma-pdf. The statistical moments of the model has closed form expressions. Models in common use also can be derived from it when the parameters are set to some specific values, so in this aspect it's generalized form of the statistical model for infrared image. The estimation of parameters can be done via the statistical moments. Furthermore, the infrared image can be segmented properly based on the model.