  In this paper we give the new sufficient conditions of entanglement for
multipartite qubit density matrixes. We discuss in detail the case for
tripartite qubit density matrixes. As a criterion in concrete application, its
steps are quite simple and easy to operate. Some examples and discussions are
given.
  PACC numbers: 03.67.Mn, 03.65.Ud, 03.67.Hk.
