Rapid development of the hickory (Carya cathayensis Sarg.) industry and excessive use of herbicides as well as other intensive management practices have resulted in serious damage to soil properties and forest vegetation. A decline in soil nutrients and a reduction in soil microbial biodiversity are often observed. To evaluate the potential of sod-culture to improve soil fertility and microbial activities of C. cathayensis forest soil, a 2-year field trial was initiated in 2010. In this study, six treatments (white clover, rye grass, oil rape seed, milk vetch, natural weeds and clean tillage (as CK)) each with three replicates were assessed in a randomized design. The effects of sod-culture treatments on soil nutrients and soil microbial biomass carbon in the C. cathayensis forest soil were measured. Changes in soil microbial diversity were also evaluated using Biolog. The results showed that there are various degrees of change in soil organic matter, available N, available K, available P, total N, total K and total P in C. cathayensis forest soil due to the different sod-culture treatments. Data indicated that except for soil total K, sod-culture treatments enhanced soil nutrient content significantly in the C. cathayensis forest soil as compared with the CK treatment. White clover and milk vetch treatments increased soil nutrient content to a greater extent than the other treatments. There was no significant difference in soil nutrient content between the remaining treatments. Sod-culture treatments increased soil microbial biomass carbon (MBC) in C. cathayensis forest soil as compared with the CK treatment. White clover, rye grass, oil rape seed, milk vetch and natural weed treatments significantly (P < 0.05) increased MBC by 169.6%, 159.7%, 144.1%, 138.6% and 58.6%, respectively. There were differences in soil microbial activity, Shannon diversity and uniformity indices between the six treatments. The Average Well Color Development sequence is as follows: white clover > milk vetch > oil rape seed > natural weeds > rye grass > CK. The Shannon index sequence is as follows: white clover > natural weeds > oil rape seed > milk vetch > rye grass > CK. The uniformity index sequence is as follows: white clover > milk vetch > oil rape seed > natural weeds > rye grass > CK. The Shannon index and uniformity index results were relatively uniform among different treatments. Using the Biolog 96 h absorbance values, principal component analysis was performed using Data Processing System software. The front nine principal components were extracted from the principal component analysis and their cumulative contribution accounted for 86.98% of the total variance. The variance contribution rates of PC1 and PC2 were 33.20% and 11.51%, respectively. The first two principal components (PC1 and PC2) were used for the analysis of soil microbial community functional diversity. The results showed that there is an obvious differentiation in the PC axis of different treatments. The PC1 axis distinguishes the white clover treatment and CK treatment from the other treatments. The white clover treatment sits on the most positive side of the PC1 axis, while the CK treatment sits on the negative side of the PC1 axis. Correlation analysis showed that there were significant differences (P < 0.01) among microbial activity, the Shannon diversity index and the uniformity index in any paired comparison, although there was no significant difference between these three indices and the soil nutrient indices, despite the fact that they were positively correlated. In conclusion, this study showed that planting white clover, milk vetch or oil rape seed will provide the best results for improving soil nutrients and microbial properties under C. cathayensis forest.