Abstract: The objective of this experiment was to analyze the short-term effects of different organic composts on orchard soil characteristics and microbial biomass. The effects of beer sludge compost(BSC), dairy manure compost(DMC) and spent mushroom compost(SMC) on soil organic matter, NPK content, bulk density, moisture content, soil respiration, microbial biomass C, N and P (SMBC, SMBN and SMBP) in soil were studied using the pot experiment. The application amount of organic composts was about 50 g/kg. The results showed that compared to CK, the beer sludge, dairy manure and spent mushroom composts obviously decreased bulk density and increased soil porosities（P0.05）. The soil water consumption rate of CK was significantly higher than those of BSC, DMC and SMC during one week（P0.05）and was about 1.26 times of BSC, 1.24 times of DMC and 1.14 times of SMC respectively. The soil water absorption and water retention were obviously improved after applying the organic composts. The soil respiration amounts of BSC, DMC and SMC were significantly improved（P0.05） and were increased by 142.17%, 114.30% and 105.39% respectively compared to CK after half a year. The three organic composts could increase the contents of SMBC, SMBN and SMBP significantly after six months（P0.05）, the contents of SMBC were about 2.35, 1.84, 1.86 times of that of CK respectively, the contents of SMBN were increased by 135.44%, 99.16%, 90.82% compared to CK, and the contents of SMBP were 2.76, 2.19, 2.04 times of that of CK respectively. The study showed that BSC was the best treatment for soil respiration, microbial biomass and others because of its active granules, the second was DMC, and SMC was the worst.