Though phosphogypsum is not an ideal filling aggregate,the gelatinization property of the filling pulp can be improved and the service life of the pipe prolonged when coal ash which is an industrial waste that can act as activator is added as a substitute of cement in the cemented phosphogypsum filling.It is of great significance to reduce filling cost and environmental pollution and promote the utilization of industrial solid wastes as resources.This is an important direction of the development of filling technology.The result showed that the backfilling material made with phosphogypsum and fly ash can completely meet the technical demand of industrial filling.