Dye　wastewater　has　become　one　of　the　difficult　industrial　wastewaters　due　to　its　significant　characteristics　such　as　high　chroma　and　poor　biodegradability.　Here,　we　use　collagen　fibers　(CFs)　as　the　matrix,　glutaraldehyde　as　the　cross-linking　agent,　and　polyethyleneimine　(PEI)　as　the　ammoniating　modifier　to　prepare　cationic-modified　collagen　fibers　(CF-PEI).　The　CF-PEI　still　maintained　the　original　fibrous　structure　with　a　larger　adsorption　area.　The　content　of　primary　amino　groups　on　CF-PEI　was　significantly　increased,　which　not　only　improved　the　hydrophilic　swelling　performance　of　CFs　but　also　improved　the　adsorption　capacity.　The　adsorption　capacity　of　CF-PEI　for　soap　yellow　and　acid　red　could　reach　538.2　and　369.7　mg　g(-1),　respectively.　The　adsorption　rate　was　fast,　and　the　adsorption　equilibrium　could　be　reached　in　about　60　min.　Desorption　regeneration　studies　have　shown　that　0.1　mol　L-1　HCl　could　achieve　a　better　desorption　effect,　and　the　CF-PEI　had　a　good　recycling　performance.　The　ammoniated　modified　CF-PEI　was　an　excellent　adsorption　treatment　material　for　anionic　dye　wastewater.　It　is　expected　to　become　an　effective　way　for　high-value　resource　utilization　of　waste　dander　in　the　leather　industry.