The invention discloses fulvic acid complexed boron and a preparation method thereof and relates to a fulvic acid compound fertilizer and a production and preparation method thereof. The fulvic acid complexed boron comprises the following components in percentage by mass: 10 to 40 percent of fulvic acid, 40 to 80 percent of borax pentahydrate and 10 to 20 percent of elemental boron. The method comprises the following steps of: in a reaction kettle, adding water to prepare a 5 to 30 mass percent solution of the fulvic acid and the borax pentahydrate in proportion; heating the solution to over 60 to 98 DEG C; continuously stirring the solution to allow the two raw materials to be fully mixed to undergo a complex reaction to form fulvic acid complexed boron solution;after the reaction is carried out for 2h, injecting the fulvic acid complexed boron solution into an evaporator to evaporate out water until the content of a solid effective substance is improved to 10 to 40 percent; and performing a spray drying method on the solid effective substance to obtain micro particle products. The fulvic acid complexed boron and the preparation method thereof have the advantages of saving fertilizers, enhancing the stress resistance of plants, improving quality of agricultural products, along with obvious efficiency on drought resistance, no pollution to the environment, long fertilizer efficiency and capability of effectively conditioning the soil structure, thereby being suitable for popularization and application.