The vermicompost and coconut chaff were used as soil conditioner，saline soils flooded by different concentrations of artificial seawater were used as improved objects to study the improvement effect of vermicompost co-applied with coconut chaff on saline soil.Each concentration of saline soil was conducted with no fertilizer，single application of vermicompost， single application of coconut chaff and vermicompost co-applied with coconut chaff through pot experiments to plant water spinach.The results were as follows:(1)The improvement effect was respectively the best with the ratio of 1∶2.5，3∶2.5 and 3∶3.5 of vermicompost and coconut chaff for the saline soils flooded by 20%，60% and 100% artificial seawater. The average plant height of water spinach was respectively increased by 56.1%，49.7%～50.6% and 48.6%～51.8% than the treatments of no fertilizer，single application of vermicompost and single application of coconut chaff.The average yield of single plant was 2.6～2.8，2.1 and 1.8～2.6 times that of the treatment of no fertilizer，single application of vermicompost and single application of coconut chaff.(2)The pH value of three salinity soils were changed from acidity to neutral or near neutrality by applying different proportions of vermicompost co-applied with coconut chaff.And the concentrations of soil organic matter，alkali-hydrolyzable nitrogen，available phosphorus，and available potassium of saline soils with different grades were significantly improved(P<0.01)，while the chloride ion concentration was significantly reduced(P<0.01). In conclusion，the vermicompost co-applied with coconut chaff could improve the pH value of saline soil and significantly increase the nutrient contents and reduce the chloride ion concentration of saline soil，which is more conducive to the growth and development of crops. The improvement effects of several different treatments on saline soil were vermicompost co-applied with coconut chaff>single application of vermicompost>single application of coconut chaff>no fertilizer.