Abstract: In order to improve the hydrophilic performance of conventional polyacrylonitrile fibers,the hydrophilic co-polyacrylonitrile fibers with three dimensional network structures were prepared with acrylonitrile and methylmethacrylate as monomers and N-hydroxymethyl acrylamide as potential crosslinking agent by solution polymerization,wet-spinning,post-crosslinking and alkaline hydrolyzing.The influences of the amount of potential crosslinking agent and conditions of crosslinking and hydrolyzing on the chemical structrue,thermal dynamic mechanical properties and surface morphologies of the fibers were investigated.Results show that the hydrophilic co-polyacrylonitrile fibers which can still keep fibrous form after absorbing water as much as(20 times) of fiber weight can be obtained by controlling the amount of post-crosslinking agent and conditions of crosslinking and hydrolyzing.