The Bi3+ ions doped spinel Nickel ferrite NiBixFe2-xO4 (NBF) where, x = 0, 0.025, 0.050, 0.075, 0.1, 0.125, 0.150 was synthesized by sol-gel auto combustion method. The properties of prepared NBF were studied by using X-ray diffraction, UV-Vis spectroscope, Vibrating Sample Magnetometer, Fourier Transform Infrared Spectroscopy, Atomic Force Microscope, Scanning electron microscope, etc. X-ray diffraction showed that increasing the concentration of Bi3+ ions led to a decrease in crystallite size from 34 to 11 nm and lattice parameters ranging from 8.339 to 8.315 angstrom, confirming the formation of single-phase cubic spinel structure NBF also the crystallite size calculated by using Williamson Hall plot, is 15 to 36 nm. The energy band gap studied using UV-Vis spectroscopy decreases from 1.510 to 1.418 eV. The dielectrics and AC conductivity of NBF were studied by LCR-Q meter by varying frequency.