,respectively. It suggested that the positive impact of biochar application on improving soil organic carbon was greater than that of straw. The application of biochar had protective function on soil original organic carbon. Biochar promoted the straw mineralization and resulted in positive interaction effect between biochar and straw on mineralization of soil organic carbon. The application of straw increased soil microbial biomass carbon (MBC) greatly, while biochar had less impact on MBC. The application of straw and biochar also increased soil microbial biomass carbon, but the interaction effect could be positive or negative, which was dependent on the incubation time or application rate.