The invention provides a method for manufacturing a diversion layer nonwoven fabric. The method comprises the following steps: producing coarse denier nano-silver fibers with the denier being 4.0-7.0D; producing fine denier nano-silver fibers with the denier being 1.0-2.4 D; respectively adding the coarse denier nano-silver fibers and fine denier nano-silver fibers into two carding machines of adouble-carding and double-crossing device, carding the coarse denier nano-silver fibers by using the first carding machine to obtain a coarse denier nano-silver fiber web, and carding the fine deniernano-silver fibers by using the second high-speed random carding machine to obtain a fine denier nano-silver fiber web; allowing the fiber webs to enter a web laying process, and laying the coarse denier nano-silver fiber web on the fine denier nano-silver fiber web to obtain a composite fiber web; and carrying out hot air reinforcement on the composite fiber web by a hot air reinforcement machine. The double-carded nonwoven fabric is produced through manufacturing a coarse denier nonwoven fabric by using the upper layer coarse denier nano-silver fibers and the lower layer fine denier nano-silver fibers, and the permeability of the upper layer coarse denier nonwoven fabric is greater than the permeability of the fine denier nonwoven fabric to form gradient liquid absorption in order to make the surface dry.