Abstract: 【Objective】 To explore the effects of different amounts of biochar on the microbial diversity characteristics of turf-grass soil, and to provide a theoretical basis for the application of biomass in turf-grass soil.【Method】 Taking turfgrass soil as the research object and no biochar as the control, four biochar dosage treatments of 8, 20, 40 and 200 kg/m² were set, control and four treatments were marked as BC0, BC8, BC20, BC40 and BC200. After 5 months of sowing, 0-30 cm soil was collected, the contents of soil organic carbon, total nitrogen, water-soluble carbon, microbial biomass carbon and the structure of soil microbial carbon metabolism group were measured, and the effects of different amounts of biochar on turf-grass soil microbial carbon metabolism community were analyzed.【Result】 Compared with the control BC0, the total nitrogen content of soil treated with biochar increased significantly(P<0.05, the same below), the soil organic carbon of BC40 and BC200 increased significantly, the water-soluble carbon of BC200 increased significantly, but the soil microbial biochar did not change significantly(P>0.05). The average well color development(AWCD) of soil treated with BC20 was 12.4% higher than that of the control BC0, and the AWCD value of soil treated with BC200 was 51.3% lower than that of the control. BC20 increased the average optical density of biological community structure, and the microbial activity was significantly improved due to the use of amines;BC200 reduced the number of soil microorganisms and had the least negative impact on the use of polymer microorganisms. The results of principal component analysis showed that the first principal component could explain 86.06% of the variation. It was caused by six carbon source substances such as tween 40, tween 80, L-serine, D-galactose acid lipid, D, L-α-glycerophosphateand 4-hydroxybenzoic acid, which could effectively distinguish turf-grass soil treated with appropriate amount(BC8, BC20, BC40) and excessive(BC200) biochar content. The results of correlation analysis showed that there was a significant positive correlation between soil microbial biochar and the optical density of i-erythritol. The contents of soil organic carbon and water-soluble carbon were significantly or extremely(P<0.01) negatively correlated with the optical density of L-arginine, L-serine and other carbon sources.【Conclusion】 Appropriate application of biochar can improve the number and activity of microorganisms in turf-grass soil. The turf-grass soil with biochar has strong ability to utilize L-arginine and L-asparagine, but weak ability to utilize carbon source substrates such as L-threonine, i-erythritol, D-xylose and 2-hydroxybenzoic acid. It is suggested that when planting turf-grass grass, the application amount of biochar should be controlled within 20 kg/m².