TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preparation: Preparation method of magnetic solid base catalyst for biological diesel production comprises dissolving silicate in water at 10-100 degrees C and having 100-900% mass of the silicate to form sol, adding the magnetic matrix in according mol ratio between silicon to the metallic element iron (Fe) or nickel (Ni) or cobalt (Co) being 1:1-10:1 for performing magnetic core dispersion, so that the magnetic matrix surface is wrapped with silicate coating, vacuum drying it for 0.5-2 hours at 30-100 degrees C, calcinating it for 0.5-5 hours at 150-800 degrees C, grinding and screening the cooled catalyst to prepare magnetic solid base catalyst with grain size of 20-100 meshes. Preferred Components: The silicate includes sodium silicate, potassium silicate, or their mixture in any proportion. The magnetic matrix of Fe 3O 4, Ni 2O 3 and Co 2O 3 powder is nanometer grain. Preferred Parameters: The grain size of the catalyst is 20-100 mesh, grain size of the magnetic matrix of the Fe 3O 4, Ni 2O 3 and Co 2O 3 powder is not greater than 20 nm. Preferred Process: The magnetic core dispersion applies mechanical agitation dispersion and/or ultrasonic dispersion, or firstly mechanical agitation dispersion and ultrasonic dispersion. The process of mechanical agitation dispersion is mechanically agitating for 10-200 minutes at 20-100 degrees C and with speed of 100-900 rotations/minute; the process of ultrasonic wave agitation is ultrasonically agitating for 10-180 minutes at 20-100 degrees C and with ultrasonic work frequency as 20-100 KHz, and having ultrasonic power of 20-1000 W. Preferred Conditions: The reaction condition of oil and low carbon alcohol, magnetic solid base catalyst in the backflow condensing device with agitation function is the mol ratio of the low carbon alcohol to the oil is 3-30:1; the low carbon is 1-20 % mass of that of the oil, the reaction temperature is 40-100 degrees C, agitation speed is 100-800 rotations/minute, and the reaction time is 0.5-5 hours. The reaction condition of oil and low carbon alcohol, magnetic solid base catalyst in the fluidized bed having exterior magnetic field is as: strength of the exterior magnetic field is 0.01-0.05 T, liquid flowing speed is 1-10x 10 -2 m/second, the reaction temperature is 20-100 degrees C, the reaction time is 1-5 hours, the mol ratio of the low carbon alcohol to the oil is 3-30:1; and low-carbon is 1-20% mass of that of the oil.