Soil samples were collected from a long\|term experiment site located at Shenyang Agricultural University initiated from 1987 and soil pH, organic carbon, total nitrogen, hydrolysable nitrogen, Olsen\|P, available potassium, microbial biomass carbon and nitrogen, and average well color development (AWCD) of BIOLOG GN plate were analyzed to examine the complex effects of long\|term fertilization and plastic film covering on some soil fertility and microbial properties. Results showed that under conventional cultivation, microbial function indicated by AWCD was affected by fertilization through its impacts on soil organic carbon, Olsen\|P and available potassium contents, indicated by the significant correlations between AWCD and these indices (p<0.01). Compared to conventional cultivation, plastic film covering cultivation stimulated maize development and aboveground biomass, and changed soil pH and C/N ratio. Under the plastic film covering cultivation, AWCD was correlated significantly with soil pH and C/N ratio (p<0.01), but not significantly with soil organic carbon and Olsen\|P contents (p>0.05), indicating that plastic film covering affected microbial function through its impacts on soil pH and C/N ratio.