Powdered natural rubber can be prepared by using gamma-rays vulcanization and special drying method from natural rubber latex (NRL). This kind of powdered natural rubber would be expected to toughen plastics as an impact modifier and the property of natural rubber depends on its crosslinking degree. Therefore, it is necessary to study the crosslinking behavior of NRL under gamma irradiation. In the paper, the NRL was vulcanized with i-octyl acrylate (OA) as a crosslinking sensitizer under gamma irradiation. The influences of absorbed dose, dose rate and crosslinking concentration were discussed. The radiation vulcanization of NRL depends significantly on absorbed dose and crosslinking sensitizer content. The gel fraction of NR increased with absorbed dose and OA content, and it increased slightly above 10kGy. With increasing dose rate, the gel fraction decreased slightly. The highest gel fraction (about 90%) reached at dose of 25kGy with 5% OA. In the system, the radiation crosslinking behavior of NRL with OA as a crosslinking sensitizer could be described well with Charlesby-Pinner equation and ,G,(x) was calculated to be about 3.8.