NOVELTY - Forming basic ionic liquid modified magnetic nano-particle catalyst involves preparing alkaline ionic liquid in kettle, adding N-methyl imidazole/chloropropyl triethoxy silane to toluene to give pure (Smim); adding (Smim)Cl and potassium hydroxide to anhydrous methylene dichloride to give alkaline ionic liquid (Smim)OH; mixing ferrous salt with ammonia water to give magnetic ferric oxide (Fe3O4) nano particle; dispersing alkaline ionic liquid modified magnetic nano-particle catalyst and magnetic Fe3O4 particle in anhydrous toluene and adding (Smim)OH to magnetic Fe3O4 nano-particle.    USE - For synthesizing a basic ionic liquid modified magnetic nano-particle catalyst (claimed), useful for synthesis of bio-diesel.    ADVANTAGE - The process has high catalytic efficiency; has reduced production cost; and has simple operation.    DETAILED DESCRIPTION - Synthesizing a basic ionic liquid modified magnetic nano-particle catalyst involves preparing alkaline ionic liquid in the reaction kettle, adding N-methyl imidazole and chloropropyl triethoxy silane to 10-50 ml toluene solvent, for 24 hours at 40-85 degrees C, and refluxing for till the layering, washing using 10-60 ml ethyl acetate for three times, separating the lower layer liquid, vacuum drying to obtain the pure (Smim); adding (Smim) Cl and KOH to 10-50 ml anhydrous methylene dichloride, stirring at room temperature for 5-24 hours, filtering, rotatably evaporating to remove the solvent, washing using 10-60 ml diethyl ether for 3 times, vacuum drying at 80-110 degrees C for 8-24 hours to obtain alkaline ionic liquid (Smim) OH; mixing ferrous salt with 25 wt.% ammonia water and stirring for 20 minutes, then raising the temperature to 60 degrees C to stir for 10 minutes, then using magnetic separation, washing with de-ionized water, at 80-110 degrees C, drying in vacuum for 24 hours to obtain magnetic ferric oxide (Fe3O4) nano particles; dispersing alkaline ionic liquid modified magnetic nano-particle catalyst, and the obtained magnetic Fe3O4 nanometer particle, in 20-40 ml anhydrous toluene, adding a (Smim) OH to magnetic Fe3O4 nano-particle with mole ratio of 0.4:1 to 0.20:1 at 80-100 degrees C, stirring and refluxing, extracting methylene dichloride for 16-28 hours at 80-100 degrees C, and drying for 24h hours in vacuum to obtain alkaline ionic liquid modified magnetic nano-particle catalyst (Smim) OH/ferric oxide (Fe3O4).