Soil organic carbon has been considered as a key factor to restrict crop growth and yield. The aim of this study was to evaluate the positive effect of biochar application combing with wormcast on improving soil organic carbon to increase crop yield in medium-low yield farmland. A pot experiment was carried out to reveal changes in soil organic carbon and rice yield of different treatments. Seven treatments were conducted such as no biochar and wormcast treatment as CK，two level of biochar application as 6 g·kg-1(B1) and 30 g·kg-1(B2) and 3 lever of wormcast application as 0(M1)，1%(M2) and 5%(M3) in weight. There were no significant differences in soil temperature and rice height among the 7 treatments with biochar and wormcast application. Soil organic carbon increased significantly in 6 g·kg-1 biochar and 5% wormcast combined application treatment or 30 g·kg-1 biochar with or without wormcast application treatments. Soil organic carbon significantly correlated with the amount of carbon input from biochar and wormcast，the correlation coefficient was 0.851(P<0.05). Biomass of different parts of rice with 30 g·kg-1 biochar application treatments were higher than that of 6 g·kg-1 biochar application treatment under the same amount of wormcast application. The grain weight of B1M3 and B2M3 were higher than other treatments and the primary cause was that the application of biochar and wormcast increased nutrient input and promoted nutrient uptake，and the nitrogen harvest index increased，compared with CK. Biochar and wormcast combined application is an effective measure to increase soil organic carbon as fertilizing soil quality and increasing nutrient absorption and utilization and so can increase rice production for medium-low yield farmland.