Abstract: 【Objective】 The study aimed to explore the effects of different of ecological earthworms on soil quality and microbial community structure in coastal saline-alkali farmland， reveal the mechanism by which earthworms restore saline-alkali soil in coastal areas， which would provide theoretical basis for the restoration and improvement of saline-alkali soil in coastal areas. 【Method】 Taking the soil from coastal saline-alkali farmland as the research object， two ecological types of earthworms， namely Eisenia fetida and Pheretima guillelmi， were selected as the experiment materials. Five treatments were set up： low-density （30 earthworm/bottle） Eisenia fetida （SE1）， high-density （90 earthworm/bottle） Eisenia fetida （SE2）， low-density（10 earthworm/bottle） Pheretima guillelmi （SP1）， high-density （30 earthworm/bottle） Pheretima guillelmi （SP2）， and no earthworm addition （CK）. The indicators related to physicochemical properties of the soil and the enzyme activity were measured， the changes in the structure of the soil microbial community were studied， and RStudio was adopted to analyze the correlations between the soil microorganisms and environmental factors. 【Result】 The analysis of soil physicochemical properties showed that the treatment with earthworms could reduce the total salt content and organic matter content of coastal saline-alkali soil， and increased the pH and humus content. After 40 d of cultivation， the total salt content of SE1， SE2， SP1， and SP2 treatments was significantly decreased by 16.26%-20.73% compared to that of CK （P<0.05， the same below）； the organic matter content was significantly decreased by 5.75%- 12.18% compared to that of CK； pH was increased by 0.29-0.44 compared to that of CK； and the humus content was significantly increased by 27.11%-37.20% compared to that of CK. Earthworm treatments could increase the total nitrogen， ammonium nitrogen， and nitrate nitrogen contents in coastal saline-alkali soil. Soil enzyme activity analysis indicated that except for the 0^th d， the earthworm treatment could also increase the urease， sucrose enzyme and peroxidase activities of coastal saline-alkali soil； on the 40^th d of cultivation， compared with CK， the urease activity significantly increased by 21.84%-31.74%， the sucrose enzyme activity significantly increased by 52.63%-67.89%， and the peroxidase activity significantly increased by 22.96%-35.54%. The analysis of microbial community structure showed that earthworm treatment could increase the relative abundance of Sphingomonadaceae， Xanthomonadaceae， Gemmatimonadaceae， Chitinophagaceae， Nitrosomonadaceae， and Comamonadaceae. The correlation analysis results indicated that Nitrosomonadaceae， Chitinophagaceae， Xanthomonadaceae， Comamonadaceae， and Gemmatimonadaceae were all significantly negatively correlated with total salt content； while Xanthomonadaceae， Sphingomonadaceae， Chitinophagaceae and Gemmatimonadaceae were all significantly positively correlated with nitrate nitrogen content， ammonium nitrogen content， and urease activity. 【Conclusion】 Adding earthworms with different ecological types and densities can improve the physicochemical properties of the soil， enhance nitrogen cycling and related enzyme activities， regulate the structure of the microbial community， promote nitrogen transformation in saline-alkali soil， accelerate the reduction of soil salt content， and effectively restore and improve coastal saline-alkali soil. Among them， the combined effect of high-density Pheretima guillelmi treatment is the best.