NOVELTY - Magnetic solid base catalyst for biological diesel production comprises magnetic matrix and silicate coating wrapped out of the magnetic matrix, where magnetic matrix includes hydroxyl ferrous powder, ferrous-ferric oxide (Fe 3O 4), dinickel trioxide (Ni 2O 3) and dicobalt trioxide (Co 2O 3) powder.    USE - The magnetic solid base catalyst is useful for biological diesel production (claimed).    ADVANTAGE - Magnetic solid base catalyst for biological diesel production simplifies processes, reduces production cost of the biological diesel, and decreases pollution. When the magnetic solid base catalyst is applied to reaction for preparing biological diesel by oil ester exchange, permanent magnet or magnetic field realizes efficient and rapid separation and recovery of the catalyst and products, furthermore, the recovered catalyst is in no need of activation process, which can be used for biological diesel conversion for 11-20 times with conversion rate greater than or equal to 96 % and yield greater than or equal to 99 %, the product quality index meets the standard of GB/T 20828-2007. Moreover, the prepared biological diesel product is in no need of post treatment as neutralization or washing.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are:    (1) preparation of magnetic solid base catalyst for biological diesel production; and    (2) use of magnetic solid base catalyst in biological diesel production which includes adding prepared magnetic solid base catalyst and oil, low carbon alcohol into backflow condensing device or magnetic field fluidized bed having agitation function according to certain proportion for reaction, using permanent magnet or magnetic field for absorbing and recovering the magnetic catalyst, preparing upper layer of fluid phase product; stewing and layering it to prepare coarse biological diesel and glycerine phase, respectively distilling the coarse biological diesel and the glycerine phase to prepare low carbon alcohol, thereafter, neuter biological diesel and glycerine are prepared.