In this paper, the behavior of SU(2) squeezing of the mixed-state in two-level atom are studied by means of the time-evolution operator method. We have obtained new results that the mixed-state atomic squeezing under interacting of the light field is deeper than the general pure-state atomic SU(2) squeezing. Furthermore, the squeezing value of the atom in pseudo-ground state is more greater than that in pseudo-excited state. The relation between the statistical probability of atomic level population and the squeezing is studied by numerical calculations.