NOVELTY - Preparation of microwave-assisted iron-oxidizing compound nitrogen carbon nanotube catalyst includes adding iron/Santa Barbara Amorphous-15 (Fe/SBA-15) molecular sieve into porcelain boat, heating in quartz tube-type furnace, passing argon/organic amine mixture, naturally cooling, diluting in hydrogen fluoride solution to remove catalyst mixture, adding black nanotube into polyhydric alcohol solution, ultrasonically dispersing, adding mineralizing agent, stirring, adding into closed reaction container, heating, washing precipitate with anhydrous ethanol and deionized water, and drying.    USE - Method for preparing microwave-assisted iron-oxidizing compound nitrogen carbon nanotube catalyst used for production of biodiesel (claimed).    ADVANTAGE - The catalyst is easy to recover, has high catalytic efficiency and it can be repeatedly used.    DETAILED DESCRIPTION - Preparation of microwave-assisted iron-oxidizing compound nitrogen carbon nanotube (FeOx/CNx) catalyst comprises:    (A) adding Fe/SBA-15 molecular sieve into porcelain boat, heating in quartz tube-type furnace at 800-1200 K, passing 10-500 mL/minute of argon/organic amine mixture, keeping for 0.5-1.5 hours and naturally cooling to obtain black CNx nanotube and Fe/SBA-15 catalyst mixture;    (B) diluting in hydrogen fluoride solution to remove Fe/SBA-15 catalyst mixture, weighing 5-10 g black CNx nanotube, adding into polyhydric alcohol solution and ultrasonically dispersing to obtain first solution;    (C) adding 20-30 g mineralizing agent at room temperature and atmospheric pressure and stirring to obtain second solution; and    (D) adding into closed reaction container, heating at 100-250 degrees C for 8-30 hours, washing precipitate with anhydrous ethanol and deionized water, and drying.    An INDEPENDENT CLAIM is included for production of biodiesel comprising stirring soybean oil, methanol, cosolvent and microwave-assisted iron-oxidizing compound nitrogen carbon nanotube catalyst, heating at 30-120 degrees C for 20-180 minutes, standing, washing with water until neutral, drying and filtering.