In this study, we first revealed a "robbing behavior" during the immobilization of nZVI particles onto an electrospun polyacrylic acid (PAA)-polyvinyl alcohol (PVA) nanofiber mat. The robbing behavior can significantly reduce the number of nZVI particles immobilized onto the mat and hence weaken the performance of mitigating contaminated water. To minimize the undesirable effect of robbing behavior, we developed a dipping method that enables exposure of enough free Fe (II) as electron acceptors to the Fe (II)-complexed PAA-PVA mat for the subsequent reduction. The result indicates that the mat with dipping can immobilize more than 1.7 times the weight percentage of nZVI particles for the mat without dipping. Moreover, the dipping method can also re immobilize or enrich nZVI particles on the mat that has already partially immobilized nZVI particles. The nZVI-immobilized mat dipped once into the FeSO4 solution with a very little concentration (0.32 g/L) had an excellent performance for trichloroethylene (TCE) degradation (more than 92% TCE removed). Here, the developed dipping method shows great potential for nZVI immobilization and groundwater remediation.