NOVELTY - Bamboo charcoal particles are dissolved in distilled water and stirred, to obtain bamboo charcoal solution. Ferric chloride hexahydrate and ferrous chloride tetrahydrate are added to bamboo charcoal solution, dissolved, reacted, aged, washed with distilled water, filtered, and dried to obtain bamboo charcoal-iron(II,III) oxide magnetic carrier. The obtained carrier is placed in a container, potassium nitrate solution is added, stirred for 3 hours, dried in a muffle furnace, and cooled to room temperature, to obtain bifunctional magnetic solid alkali catalyst.    USE - Preparation of bifunctional magnetic solid alkali catalyst used for producing biodiesel (claimed).    ADVANTAGE - The method enables preparation of environmentally-friendly bifunctional magnetic solid alkali catalyst. Biodiesel is economically produced using the bifunctional magnetic solid alkali catalyst with high reaction speed.    DETAILED DESCRIPTION - 5-10 g Bamboo charcoal is pulverized in a crusher, and sieved with 80-mesh sieve, to obtain bamboo charcoal particles. The obtained particles are dissolved in 500 ml distilled water, and stirred for 2 hours to obtain bamboo charcoal solution. 9.731 g Ferric chloride hexahydrate and 3.5786 g ferrous chloride tetrahydrate are added to bamboo charcoal solution, dissolved, stirred for 1-2 hours, dripped in aqueous ammonia having pH value of 11 using a dropping funnel, reacted for 1-2 hours, aged for 1-3 hours, washed with distilled water until it is neutral, filtered, and dried, to obtain bamboo charcoal-iron(II,III) oxide magnetic carrier. The obtained carrier is placed in a container, 10-30% potassium nitrate solution with potassium nitrate content of 10-50 %mass is added, stirred for 3 hours, dried in a muffle furnace at 400-600 degrees C for 1-4 hours, and cooled to room temperature, to obtain bifunctional magnetic solid alkali catalyst. An INDEPENDENT CLAIM is included for usage method of bifunctional magnetic solid alkali catalyst for production of biodiesel.