Based on the indoor simulation experiment, the effects of amendment (biochar and calcium peroxide) on microbial biomass carbon, nitrogen and dissolved organic carbon and nitrogen in upland red soil were studied. The experiment included 4 treatments, namely CK, Ca (calcium peroxide, 1.72 g/kg), C (biochar , 21.46 g/kg), and C+Ca. The results showed that soil microbial biomass carbon, nitrogen and dissolved organic carbon had the same change tendency, which increased rapidly within 3 days, and reached the maximum on the third day, and then decreased with the time. Additionally, the effect of combined application of the two amendments was better than that of single application. The dissolved organic nitrogen increased slowly within 21 days; compared with CK, dissolved organic nitrogen under C+Ca, Ca, C treatments significantly increased by 62.1%, 55.5%, and 40.9% on twenty-first days, respectively; after 35 days, the effects of C+Ca and Ca was significantly better than those of C and CK. During the 120 day incubation period, C+Ca treatment could significantly improve the average content of microbial biomass carbon, nitrogen and dissolved organic carbon and nitrogen; the ranking of average content of microbial biomass carbon from high to low was: C+Ca>C>CK>Ca, and the average content of microbial biomass nitrogen in C+Ca treatment was significantly higher than those of other treatments. the ranking of average content of soluble organic carbon was C+Ca>Ca>C>CK, and they were significantly higher in C+Ca and Ca than those of CK and C. There was a significant positive correlation between microbial biomass carbon, nitrogen and dissolved organic carbon (P<0.01), but there was a significant negative correlation between microbial biomass carbon and dissolved organic nitrogen. Therefore, biochar and calcium peroxide can effectively improve soil microbial biomass carbon, nitrogen and dissolved carbon and nitrogen in upland red soil, and the combination of biochar and calcium peroxide is more beneficial to soil improvement.