The invention discloses an internal nitriding preparation method of an aluminum nitride dispersion strengthened copper composite material. The method comprises the steps of pretreatment, sintering, thermal deformation, rotary forging and fine rolling. By adopting the method, the problem of high impurity oxygen content and complete freedom from hydrogen embrittlement in the aluminum nitride dispersion strengthened copper composite material is solved, the problem of coarse particles of aluminum nitride in a composite aluminum nitride-copper composite material prepared by mechanical ball millingis solved, and the problems of cracking, low strength and the like caused by excessive chromium in a process of preparing an aluminum nitride composite material from chromium nitride are solved.