Using the theory of information entropy squeezing, the entropy squeezing of a two-level atom in an atomcavity- optomechanical system is investigated. The influences of the coherent angles of the atom, the coupling coefficient between the cavity field and the mechanical mode, and the relative phase of the two atom level on the entropy squeezing of the atom are discussed. It is shown that the squeezing amplitude, squeezing frequency and squeezing direction of the atomic information entropy squeezing can be controlled by choosing the suitable coherent angle of the atom, coupling coefficient between the cavity field and the mechanical mode and the relative phase of the two atom level, respectively; and the atomic optimal entropy squeezing states in the system can be prepared by controlling the coherence angle of the atom. The proposal may provide a theoretical way to control entropy squeezing of the atom in the atom-cavity-optomechanical system.