The invention discloses process equipment for preparing strong acid ion exchange fiber. The process equipment comprises a liquid storage tank, a reaction kettle, a water bath heating circulation device, a condensation reflux device, a tail gas absorption device and a vacuum pump. The process comprises the following steps: swelling fiber to be sulfonated for 6-12 hours with a swelling agent; adding sulfonation liquid from the bottom of the reaction kettle, and gradually heating to finish a sulfonation reaction; at the end of the sulfonation reaction, recovering the sulfonation liquid back into the liquid storage tank once again, distilling under reduced pressure to remove the swelling agent adhering to the surface of the fiber, and collecting the vaporized swelling agent into the liquid storage tank in a reflowing way through condensation; at the end of distilling under reduced pressure, performing split charging on strong-acid-based ion exchange fiber for storage in order to avoid acid gradient washing. A certain amount of diluted solution of chlorosulfonic acid is supplemented into the sulfonation liquid, the sulfonation liquid can be used circularly, and fiber sulfonation is continued to prepare the strong acid ion exchange fiber. A sulfonation method has the advantages of simple preparation process, remarkably-lowered cost, no need of acid liquid gradient washing, no emission of any waste liquid, circular use of sulfonation liquid, and the like.