The present work was carried out to study the effect of prepared chitosan nanoparticles (CNPs) on the dye ability of silk fabric dyed with mono and bi functional reactive dyes. In order to obtain the optimum condition of using nano chitosan the silk fabric was treated with different concentration of nano-chitosan using three different methods (a)pre-treatment,(b)one bath process and (c)post-treatment. The colour strength (K/S) and colour parameters of dyed silk samples were measured for each method. The change in silk fabric surface morphology after using nano chitosan was examined with SEM. The K/S results of silk dyed samples treated with nano chitosan solution were higher comparable to the untreated samples.furthermore nanochitosan exhibit superior behaviour as antibacterial agent against both gram-positive and negative bacteria .