The decomposition of organic matter and the succession of different soil fauna population during this process were studied under four different soil fertility maintaining treatments at Quzhou experimental Station of Hebei Province. The results showed that the numbers of some main soil fauna—excluding nematodes - differed between treatments with the highest number in the compost plot (OF followed by the untilled plot (OR) and the control plot (CK) with the lowest numbers in the chemical fertilization plot (CF). This trend was in accord with the trend of decomposition rate in the different treatments. In the compost plot, the control plot and the chemical fertilization plot, bacterial-based food webs play the main role in regulating organic matter decomposition. Contrary to this, fungal-based food web plays a larger role in regulating organic matter decomposition in the untilled plot.
At the initial stage of the decomposition, the biomass of bacteria was greater, the number of protozoa increased, and so did the number of earthworms under all treatments. At the late decomposition stage, the biomass of fungi and the number of earthworms decreased, which was correlated with a decreasing decomposition rate. Gray correlation analysis was used to study the relationships between the organic matter decomposition rate and environmental or biological factors. The most important regulating factors in descending sequence were Soil temperature (0.844), Number of earthworms (0.777), fungi (0.764), total nitrogen (0.754), Numbers of nematodes (0.753), Soil organic matter（0.742), Numbers of bacteria（0.738）, protozoa（0.693） and soil moisture（0.661）,Therefore, soil temperature and the number of earthworms were the main factors that affected the organic matter decomposition rates.