NOVELTY - Repairing heavy metals in waste compost by using waste barrier of nitrilotriacetic acid (NTA), comprises: taking Festuca arundinacea L as the test material, test waste compost; taking a barrier material comprising zeolite, vermiculite and sawdust, drying the material; filling dry garden soil into PVC pipe, adding barrier layer, adding compost; seeding the Festuca arundinacea in the tube, applying microbial inoculums with different concentrations and NTA sodium salt aqueous solution on surface of the compost, cradling cutting, and measuring the content of heavy metals.    USE - The method is useful for blocking downward migration of heavy metals in the compost and soil by taking 10 mmol/kg-NTA combined with an barrier layer comprising zeolite, vermiculite and saw dust (claimed).    ADVANTAGE - The obtained test result shows that: the barrier interlayer is in the middle, soil in the upper layer and compost in the lower layer, thus reducing the migration of harmful substance and heavy metal from waste compost to soil; the lawn plant is induced by the chemical chelating agent so as to increase absorption of heavy metal during composting time and in vivo enrichment of heavy metals, and to reduce the migration of heavy metal into the deep soil.    DETAILED DESCRIPTION - Repairing heavy metals in waste compost by using waste barrier of nitrilotriacetic acid (NTA), comprises:(a) taking test material: (a1) taking northern perennial Festuca arundinacea L as the test material, test waste compost from the composting plant in Tianjin small lakes, test soil from 0-20 cm deep surface layer of garden soil, air-drying the compost and garden soil respectively by 2 mm sieve; (a2) taking an barrier material comprising zeolite (20 g), vermiculite (20 g) and sawdust (20 g), drying the material at 80 degrees C; and (a3) preparing a leaching solution comprising ammonium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium nitrate, magnesium nitrate and hydrogen sulfate, where the concentrations of sulfate, nitrate, chloride, ammonium, magnesium, calcium, potassium and sodium are respectively 14.96, 6.54, 1.68, 3.71, 0.82, 1.38, 0.64, and 0.78, and adjusting the pH to 5-6 with hydrogen chloride; (b) test method: (b1) supporting the bottom of the PVC pipe with diameter of 7.5 cm, length of 25 cm on a nylon mesh with a diameter of 0.2 mm in the soil and compost, and lifting the pipe, where the lower part of the pipe is provided with a conical bottle connected with a filtrate, (b2) filling dry soil (500 g) into the PVC pipe, paving, filling barrier layer (60 g), and then reloading into compost (280 g), and paving in the barrier layer; (b3) seeding Festuca arundinacea (0.6 g) in the PVC pipe, irrigating with tap water, maintaining the whole field water to be 60-65%, frequently changing the position to ensure uniform illumination, where the illumination intensity is 350-800 mu mol m-2 s-1, the temperature and the humidity are respectively 23-30 degrees C and 30-65%, (b4) after seeding Festuca arundinacea for 30 days, applying NTA sodium salt solution (150 ml) of the 5-15 mmol/kg compost to the compost surface, after ryegrass grows for 10 days, cradling cutting, leaving 1 cm of stubble, placing the cut lawn plant of Festuca arundinacea at 80 degrees C in the oven for drying to constant weight, and recording the ground biomass, (b5) leaching for the first time (the next day after cradling) by using 150 ml of leaching solution equal to 34 mm of the precipitation, leaching once every 7 days, each time taking 150 ml of leaching solution, and spraying 3 times (totally 450 ml), respectively weighing, and collecting the same in the conical flask, and mixing them uniformly, (b6) after the leaching process, applying NTA sodium salt solution of the 5-15 mmol/kg compost to the compost surface, after growing for 10 days, cradling, and the placing the cut lawn plant at 80 degrees C in the oven for drying to constant weight, recording the ground biomass, and (b7) using TAS-990 atomic absorption spectrophotometer to measure the heavy metal cadmium, chromium, copper, lead and nickel content in the digestive liquid.