In this communication, environmental friendly and biocompatible ultrafine super-paramagnetic magnetite nanoparticles (USPMNs) ferro-fluid was prepared by modifying co-precipitation green itinerary under optimized conditions. Phase pattern of USPMNs was confirmed by X-ray diffraction (XRD). Particle size of USPMNs was also estimated using the Scherrer's formula which turned out to be almost 12 nm, confirmed by SEM image. The magnetic study of USPMNs confirmed the super-paramagnetic nature with zero coercivity and remanence. The spin glass behavior on the surface of these USPMNs below 40 K was attributed for the exchange bias effects during field cooling process as confirmed by M-T graph. The dielectric constant and dissipation factor followed the same decaying dispersion trend at room temperature. The low temperature effects on dielectric constant and dissipation factor were also studied at frequencies of 10, 20 and 30 kHz.