Abstract:The mixing property of mth order hidden nonhomogeneous Markov models is studied. At first,the definition of the mixing property of mth order nonhomogeneous Markov chains is given. Then the sufficient condition for mth order nonhomogeneous Markov chains to meet this kind of mixing property is proved by using the definition and lemma three. Lastly,the results about nonhomogeneous Markov chains are extended to the mth order hidden nonhomogeneous Markov models,which provide some theoretical basis for further studying multi-order hidden Markov models.