The invention discloses a method for preparing a flame-retardant anti-microbico polypropylene bulked continuous filament. The method comprises the following steps: A) evenly mixing magnesium sulfate whisker, basic magnesium chloride whisker, magnesium salt whisker and palygorskite, and then roasting the mixture in a vacuum stove, cooling down the mixture, stirring and dispersing the mixture in absolute ethyl alcohol by sodium hexametaphosphate, then carrying out plasma treatment at normal pressure, and then carrying out ultrasonic dispersion and cleaning in deionized water containing calcium stearate dispersion liquid, filtering the suspended whisker on the upper layer of the solution, taking modified whisker mixture liquid, repeating operation until depuration, and carrying out drying in a vacuum oven after depuration, thus obtaining modified whisker; B) stirring the modified whisker obtained from step A), antimonous oxide, hexabromocyclododecane aluminum, calcium stearate and a PP-g-MAH (maleic anhydride grafted polypropylene) bulking agent in a mixer, and adding isotactic polypropylene powder, so as to obtain flame-retardant anti-microbico isotactic polypropylene after mixing and stirring; and C) drying the flame-retardant anti-microbico isotactic polypropylene obtained from the step B) in a dynamic vacuum oven so that the moisture content is less than or equal to 30 ppm, carrying out direct extrusion through a co-rotating twin-screw melt mixing extruder and spinning, thus obtaining the flame retardant anti-microbico polypropylene bulk continuous filament with improved multiple functions.