By using co-evaporating semiconductor and insulator media,InP∶CaF2 films were prepared.Inp was embedded in CaF2 in the form of clusters,whose size could be controlled by gas pressure and evaporating electric current.Transmission electron micrographs showed that the structure of InP cluster was polycrystalline.And the cluster size is about 10nm.We studied linear optical absorption of this kind of films.Quantum effect was observed clearly.With decreasing cluster size,the blue shift of the absorption edge was found.