Field surveys were carried out to investigate earthworm species in soils in 7 land-use types in salinity transforming region of Quzhou Country, Hebei Province and indoor incubation was done to study influences of earthworm population to soil biological parameters. Results show that (1) 5 species of earthworms were found, belonging to 5 genera and 3 families, with Eisenia fetida in dominance over 60% in number of individuals, and two species of Aporrectodea trapezoides and Eisenia fetida were widely distributed in this area, the present frequency in samples were 74% and 44% respectively, as the dominant species; (2) the order of earthworm population density and biomass change tendency in different land use types was : vegetable garden > vertical no-tillage > clean-stubble no-tillage > market vegetable plot > traditional corn land > orchard > abandoned land. The earthworm average population density and biomass were highest was in vegetable garden, achieving 272 Ind. m^-2 and 68.04 g m^-2 respectively; (3) Among the relationships between earthworm population characteristics and biological properties of soils the earthworm population density and the species number were positively correlated with soil basal respiration and microbial biomass carbon content significantly (p< 0.01 ), but soil basal respiration quotient existed significantly negative correlation (p< 0.01 ); (4) the effects of earthworm population density and biomass on soil microbial communities were significant. The greater the earthworm biomass and population, the higher the contents of soil organic matter, available nitrogen, available phosphorus, available potassium, and conversely contrary. Moreover the lab experiment also indicates that soil protozoa, microbial carbon, and microbial nitrogen tended to increase with the rise of the number of earthworm individuals. The characteristics of earthworm population can also be used as indicators in evaluating soil biological fertility, just like soil biological indicators and soil chemical indicators.