Abstract: Inorganic foam filling material used in colliery, in this paper, contains the foaming agent, polypropylene fiber and the gelling agent such as ordinary portland cement, fly ash, micro silica fume. And the experimental study focused on the various elevated properties of this material by fiber. Effects of the length, quantity and the different methods of mixing of polypropylene fiber on stress of inorganic filler foam material were studied and analyzed. The conclusions are that the polypropylene fiber can improve compressive strength, breaking strength and can also effectively suppress the dry shrinkage rate of the inorganic foam filling material. Therefore, the mixing of polypropylene fiber has a good role in promoting the mechanical properties of inorganic foam filling material.