NiFe2O4 ferrite nano-particles(<20 nm) in SiO2 matrix have been prepared by sol-gel method The particle size was varied by changing the time and temperature of the heat treatment during the preparetion of the sample. X-ray diffraction study indicates the single-phase spinel ferrite in the sample. The particle size was estimeted by X-ray diffraction method as well as from Transmission Electron Microscope. The magnetic property of the sample were studied by a vibrating sample magnatometer and Mossbauer experiments. In magnetic measuremet zero histirisis loss was obtained for the particles having diameter less than 6nm. Magnetic study also indicate the change of dead layer (canted spin arrangment) volume with the particle size. The charecteristic superparamagnetic doublet was obtened for the perticles less than 5nm. For the particles having grater volume, the preasence of two finger pattern mixed with two sixfinger indecates the preasence of particle size distributio as well as the two magnetic sublatices.