Plant residues are an important source of soil organic matter. Decomposition characteristics of plant straws, soil microbial functional diversity and their relationship was studied so as to find some scientific basis for transformation of organic carbon in soil and rational exploitation of land resources. The mesh bag method was used to explore how plant straws decompose in fields of three long-term field experiments and the biolog micro plate technology was adopted to determine soil microbial community diversities in the fields of the three long-term field experiments. Results show that with decomposition going on, residue rate of fresh plant straws did not varied much. The three long-term field experiments were basically similar in this aspect, displaying an order of FB (Fresh bean stalk) > fc (Fresh corn stalk + nitrogen fertilizer) > FC (Fresh corn stalk), but residue rate of oven-dried milled corn stalk differed quite sharply. In terms of soil microbial community activity (average well color development, AWCD), the three long-term experiments followed an order of Vineyard > Peach orchard > Farmland, indicating it was the highest in the vineyard, while diversity index analysis indicates that the farmland did not differ much from the vineyard and peach orchard in all the soil microbial community indices, except for evenness, which did to a significant level. Principal component analysis of the Biolog 31 carbon sources reveals an order of farmland > Peach orchard > vineyard in terms of soil typical dispersion degree, indicating that the farmland was the lowest in microbial community stability and followed by peach orchard and vineyards. Analysis of microbial community structures utilizing the six categories of carbon sources indicates that significant differences existed between the three experiment fields in the utilization of amino acids and saccharides, while none in that of the other four. The three major indices were extremely closely related to soil temperature, soil alkalytic nitrogen and, readily available phosphorus and, stalk decomposition residual rate was negatively related to dominancy of soil microbial communities, regardless of source of the stalk, which, to a certain extent, affected the decomposition rate of straws. In the farmland low in soil microbial activity and stability, stalk residue rate varied quite sharply between the treatments. while in orchards where the soils were relatively high in soil microbial activity and stability, stalk residue rate did slightly between the treatments.