Coal gangue is a solid waste discharged in the process of coal mining. The massive accumulation of coal gangue has resulted in severe environmental problems and waste of resources. Carbon black is the most important reinforcing filler in rubber production, but its production process accompanied by a lot of environmental pollution. Coal gangue has the potential to be used as rubber filler to replace or partially replace carbon black/silica, which can make rational use of solid waste resources. However, the activation and modification process is required due to the poor affinity of rubber with the minerals contained in coal gangue. The existence form, chemical composition and the current application status of coal gangue were introduced in this paper. And the mainstream activation modification methods of coal gangue and evaluation indicators of modification effect were reviewed. The current problems in the research and application of coal gangue as rubber filler were also pointed out, including the prospect of the industrial application. Coal gangue is mainly composed of Al2O3, SiO2 and C. Used in rubber reinforcing filler, SiO2 can increase the strength of rubber, Al2O3 plays an incremental role, and the carbon surface is rich in active sites of oxygen and hydroxyl, which is easy to cross-linked with polymer molecules. The mainstream activation modification methods include mechanical modification, calcination modification, microwave modification and surface chemical modification. Through composite modification, the particle size of coal gangue is reduced, the proportion of amorphous Al2O3 and SiO2 in coal gangue is increased, and its surface properties are changed, so as to improve the dispersion and compatibility of coal gangue filler in rubber. At present, through the comprehensive evaluation of the modification effect of coal gangue filler by direct method and indirect method, it is found that the chemical modification of coal gangue surface has the most significant impact on the performance of rubber, and the selection of appropriate surface modifier can change the characteristics of rubber products. Promoting inter-industry cooperation in research, developing new surface modifiers with high quality and low price, and optimizing product detection methods is the achievement of the purpose of large-scale utilization of coal gangue rubber filler.