The invention provides a functional material prepared from copper flotation tailings and a preparation technology of the functional material to solve the problems that the resource utilization degreeof copper flotation tailings is very low and stacking disposal can damage ecological environment and threaten production safety. The technology comprises key processes as follows: (1) performing particle size screening on the copper flotation tailings to remove coarse-grained tailings; (2) performing surface activation on fine-grained tailings obtained after particle size screening; (3) performinglanthanide series loading on the fine-grained tailings obtained after surface activation treatment. The prepared functional material has good adsorption removal capacity for phosphate in water, can be applied to phosphorus removal purification of natural water and different kinds of wastewater and has greater actual application prospects and commercial development value. The harmless treatment and resource utilization of the copper flotation tailings are realized through preparation of the functional material, waste is changed into wealth, and the basic strategy of waste resource regenerationand development of circle economy is conformed.