The northeastern region of China represents the country's largest commodity grain base. The Mollisols present in this northeastern region are very suitable for farming. However, the loss of top layer Mollisols and exposure of parent material have severely threatened the ecological environment and national food security in northeastern China. The soil microbial biochemistry process is the engine required for the reconstruction for soil fertilizers. Thus, it is important to characterize the pattern of carbon utilization by soil microbial communities during the parent maturation process to understand how microbial processes contribute to soil fertility. This study focuses on the carbon utilization pattern of soil microbial communities under different long-term maturing treatments at the national observation station of the Hailun Agroecology System. The results showed that Parent-Alfalfa (PAlf), Parent Corn-Soybean+Fertilizer+Biomass cycle (PCS+F+BM), and Parent Corn-Soybean+Fertilizer+Oganic Matter (PCS+F+OM) treatments contained the highest number of microorganisms. Parent-Natural (PNat), PAlf, PCS+F+BM, and PCS+F+OM treatments increased microbial activity to the level recorded under conventional farmland treatment. Different maturing process treatments produced different carbon utilization patterns in the microbial community. In all treatments, the highest utilization rate of the carbon source was carbohydrate. Principal component analysis indicated that the microbial metabolic characteristics under PNat, Parent-No Fertilizer (PCS-F), PCS+F+BM, and PCS+F+OM processes were similar to that those under Stander Soil Corn-Soybean+Fertilizer (SCS+F) treatment. We conclude that the change in microbial community structure under different maturing processes caused variations in the carbon utilization pattern, which ultimately influenced the metabolism characteristics of the overall carbon sources.