A fluid treatment method, a fluid treatment device, a cycle separation device, a cycle treatment system, a medical device, and a computer readable storage medium are provided. The fluid treatment method intercepts the target substance in the fluid, and cyclically enriches the target substance in the enrichment pipeline. In a cycle enrichment mode, the flow rate at the inlet is equal to that of the outlet in the enrichment pipeline so as to dynamically balance a total amount of the fluid in the enrichment pipeline. The present disclosure treats the fluid sustainably, collect particular components of the fluid, and a fluid discharged from the first outlet of the enrichment pipeline is introduced into the treatment module or is returned to an original system. The present disclosure effectively avoids continuous loss of beneficial components when filtering out harmful components in the process of component separation/exchange of the fluid through membrane separation.