The reactions of dichlorotriphosphazatrien (PNCl$_2$)$_3$ with sodium metallated rayon fibers in monochlorobenzene medium were studied under various experimental conditions. Dercent Na reacted was gradually increased with the increasing concentration of reagent and also the reaction time. Kinetic study reveals that reaction is divided by two stages and cross-linking is considered to be taken place in second stage. The reaction of Cell-ONa with (PNCl$_2$)$_3$ was of second order and their rate constants are 7.84 $ imes$10-2, 11.10 $ imes$10-2, and 16.47 $ imes$10-2 mole-1sec-1 at 30, 40 and 5$0^{circ}C$, respectively and the activation energy of reaction obtained from Arrhenius plot is 7.3Kcal/mole.