Based on the utilization of coal based solid waste renewable resources such as coal gangue and fly ash and the optimization of the performance of cemented backfill material. The influence of glass fiber content, length and curing age on the transportation performance and mechanical properties of coal based solid waste cemented material and its strength mechanism were studied by means of laboratory tests. The results show that:the slump of coal based solid waste cemented material improved by glass fiber decreases with the increase of fiber length and content, all samples are greater than 200mm which can meet the requirements of transportation performance. The compressive strength and tensile strength increase first and then decrease with the increase of fiber length, and increase with the increase of fiber content; when the concentration of coal based solid waste cemented material is 79%, the optimum scheme of glass fiber is 6mm in length and 0.3% in content. The needle like and mass like products produced by the appropriate length of glass fiber can effectively improve the material strength by filling small cracks and adhering to the fiber surface. The cemented filling material improved by glass fiber can realize the recycling of coal based solid waste, and it is helpful to energy saving and emission reduction as well as to achieve the goal of "double carbon", and it has good engineering application value.