The invention discloses a process for comprehensively utilizing rare-earth ore leaching waste liquid and calcining waste heat in rare earth production, which comprises the following steps of: treating the waste water discharged after dissolving rare-earth ores by acid by using lime, to form residue containing a large amount of calcium, iron and aluminum salts; and adding sulfuric acid with a masspercentage concentration of above 70 percent into the residue for curing to prepare an aluminum sulfate molten iron finishing agent containing calcium sulfate, wherein curing is realized by comprehensively utilizing the waste heat generated by rare earth calcination and smoke chamber waste heat of a boiler. By adopting the invention, the problem of higher cost of synthesizing the conventional inorganic polymeric flocculant aluminum ferric sulfate is solved, and the problems of large amount of residue generated by waste treatment, difficulty in treatment of the residue, low temperatures of calcining waste heat and boiler smoke chamber waste heat discharged during the rare earth production, and difficulty in comprehensive utilization in the traditional rare earth smelting process are solved; the aluminum ferric sulfate containing the calcium sulfate, with high economic benefit, is prepared on the basis of the original process, and the aluminum ferric sulfate can be used as the finishing agent in the subsequent sewage treatment; and the preparation process is simple, the economic benefit is obvious, and the process is easy to popularize.