NOVELTY - Adjusting Bacillus thuringiensis fermenting fluid for growth of Festuca arundinacea comprises weighing fresh compost sample, adding into sterile water triangle flask with glass bead, oscillating, taking mother liquor, adding into test tube with sterile water, mixing, pouring into beef extract peptone solid medium containing Petri dish, coating bacterial suspension, incubating, purifying, culturing, taking filtrate, diluting, adding lawn soil into Petri dish, adding microbial filtrate, sowing Festuca arundinacea seeds, culturing, and determining germination index.    USE - The method is useful for adjusting Bacillus thuringiensis fermenting fluid for growth of Festuca arundinacea.    ADVANTAGE - The Bacillus thuringiensis microbial agent to some extent can promote the growth of lawn plants based on experimental results.    DETAILED DESCRIPTION - Adjusting Bacillus thuringiensis fermenting fluid for growth of Festuca arundinacea comprises: (i) weighing fresh compost sample (10 g), adding into sterile water (90ml) triangle flask with 20 grain glass bead, oscillating to uniformly and thoroughly disperse the microbe in the sample into the liquid, taking mother liquor (1ml) from the triangle flask with a pipette, adding into a test tube with sterile water (9ml), thoroughly mixing to obtain a dilute solution of a concentration of 101, based on this method diluting into compost diluent of concentration of 102, 103, 104, 105 and 106, taking 0.1ml of diluent with concentration of 102, 103, 104, 105 and 106 using the pipette, pouring into beef extract peptone solid medium containing Petri dish, repeating 3 times for each dilution, taking sterile water as blank control, coating the bacterial suspension onto the whole beef extract peptone solid medium using an aseptic glass scraper to uniformly disperse the microbes, and incubating the plate with beef extract peptone solid medium into a incubator at constant temperature of 37 degrees C to culture for 1 day; (ii) purifying and culturing the separated Bacillus thuringiensis for 2 generations, adding into a 250ml triangle flask with 50ml of beef extract peptone liquid medium, culturing at 37 degrees C under 180 rotations/minute, determining by turbidimetry at 600nm wavelength, drawing the growth curve of the microbe by taking the OD value of the bacterial suspension as Y-axis and culture time as X-axis, obtaining the time from Bacillus thuringiensis initial growing phase to stationary phase according to the growth curve, taking the purified Bacillus thuringiensis, inoculating into a 250ml triangle flask with Gause No.1 liquid medium (50ml), culturing to stationary phase at 37 degrees C under 180 rotations/minute for 8-12 hours, taking the stationary phase strain and calculating the viable count in broth/ml with direct microscopic count, suction filtrating the broth of the stationary phase, passing through a microporous filter membrane (0.22 mu m) after filtrating, and obtaining the microbe fermentation filtrate; (iii) taking a portion of the filtrate, diluting to 4 times and 8 times respectively, preserving; and (iv) adding lawn soil (30 g) into a Petri dish of 6.5 cm diameter, adding all kinds of microbial filtrate (150 mu l) of different concentration into the soil respectively; adding sterile liquid medium into the control group, sowing 50 grain of full tall Festuca arundinacea seeds into the Petri dish, culturing at room temperature, determining the germination index after the seeds germinating, where the room temperature is on average 18 degrees C and the humidity is on average 40%, where purifying and culturing for 2 generations refers to using the inoculation ring to stir the unpurified strain, inoculating to the prepared Gause No.1 solid medium containing plate, scoring softly from left to right, placing the Petri dish upside down in the incubator under constant temperature of 37 degrees C to culture for 1 day this process is purification generation I, picking bacterial colony from strains of purification generation I and then repeating the process i.e. purification generation II.