For the first time, magnetite (Fe3O4) nanoparticle was green synthesized using the extract of the Brassica napus flower-extract as a new adsorbent nanocatalyst. The characterizations have been done using XRD, UV-vis, SEM-EDX, FT-IR, and ED-XRF. As-prepared Fe3O4 nanoparticles were successful for the preparation of Bis-Betti bases via one-pot three component reactions of para cresol, primary diamine and substituted aromatic aldehydes to provide N, Nˉ- Bis-[(p-cresol-2-yl)-substituted phenyl-methyl]-4, 4ˉ - oxydianiline derivatives. These reactions were also studied under different conditions without any catalyst by employing conventional method, ultrasonic technique and microwave irradiation. The synthesized products have been characterized by melting point, FT-IR, 1HNMR, 13C NMR, Mass spectral data. In fact, the prepared magnetite is quite effective nanocatalyst and stable for these reactions; facile, clean with high yield products. Moreover, the magnetite nanocatalyst was recovered and reused several times without considerable loss of its catalytic activity.