NOVELTY - Method for preparing biodegradable plastic using kitchen garbage, involves passing the kitchen garbage through grille, removing solid substances, homogenizing the separated kitchen garbage, placing in a reaction kettle, heating at 80 degrees C, configuring culture of microorganism, preparing solid fermentation culture medium, Aspergillus niger seed, inoculating in liquid fermentation culture medium, performing fermentation, then performing solid fermentation culture, extracting chitin crude product, performing deacetylation, and then washing or drying product.    USE - The method is useful for preparing biodegradable plastic using kitchen garbage (claimed).    ADVANTAGE - The method is environmentally-friendly.    DETAILED DESCRIPTION - Method for preparing biodegradable plastic using kitchen garbage, involves passing the kitchen garbage through grille, removing solid substances, homogenizing the separated kitchen garbage, placing in a reaction kettle, heating at 80 degrees C, regulating pH to 4, standing, using fat, starch, stratified protein, protein and starch for configuring culture of microorganism, preparing solid fermentation culture medium by taking culture medium carrier obtained by taking corn cob, crushing, sieving and taking particles of same size, mixing starch separated from kitchen garbage, protein and corn cob carrier in a mass ratio of 2:1:5 uniformly and adding water to make the water content to 70%, boiling the culture medium, cooling the culture medium in a sterile room to 40 degrees C, preparing Aspergillus niger seed by taking the A.niger strain and inoculating the 107 plaque-forming unit (PFU)/ml A.niger strain in a Erlenmeyer flask containing liquid fermentation culture medium from the inclined surface, where the liquid fermentation culture medium (1000 ml) is prepared using 5 g glucose, 1 g yeast extract, 0.5 g peptone and 2 g magnesium sulfate, and the pH of the liquid fermentation medium is 7.2, adding glass beads, sterilizing, packing, placing in a shaker, performing shake fermentation at 28 degrees C for 72-80 hours, inoculating 5% obtained liquid inoculum in primary seed expanding culture medium in the Erlenmeyer flask, then inoculating 0.5% liquid inoculum in secondary seed expanding culture medium in the Erlenmeyer flask, where the culture medium comprises 3% glucose, 1% peptone, 5% kitchen garbage dry extract, 1% magnesium sulfate and water (to make up to 1000 ml), again taking the solid fermentation culture which is cooled to 40 degrees C and inoculating the A.niger strain in a mass ratio of 10:1, stirring uniformly, spreading in forced ventilation packed bed reactor to thickness of 30 cm, supplying oxygen, during pre-fermentation controlling the temperature to 30 degrees C by blowing oxygenation and ventilating, where the temperature change and moisture change is controlled to 2-3 degrees , during mid-fermentation increasing the fermentation temperature to 36-38 degrees C, then spraying, high power air-conditioning or blowing air to reduce the fermentation temperature, during post-fermentation reducing the fermentation bed temperature and increasing culture room temperature to 35-37 degrees C, where the moisture content is gradually reduced to 25%, taking fermentation product, placing in a extracting kettle with water in a ratio of 1:3, stirring to adsorb to the carrier cells eluted by filtration, filtering mycelium, washing, collecting filtrate, centrifuging the filtrate to perform solid-liquid separation, and recover solid mycelium, grinding the mycelium, adding 2% sodium bicarbonate solution, heating at 95 degrees C for 2 hours, removing protein, cooling to room temperature, centrifuging, removing supernatant, washing precipitate using water until neutral, adding 40 times 10% acetic acid solution, refluxing at 60 degrees C, centrifuging, performing decalcification to obtain chitin crude product, adding 40% sodium bicarbonate into the chitin crude product at 85 degrees C for 20 hours, performing deacetylation by centrifuging, washing precipitate with water until neutral, and then washing using 95% ethanol and propanol or drying to obtain white chitosan product, which is a biodegradable plastic.