The decrease of microbial diversity in acidified soil is an important reason for the loss of soil nutrients，the high incidence of soil borne diseases and the decrease of crop yield and quality.The application of alkaline soil amendment is an effective means to improve the physical and chemical characteristics of acidified soil，reduce the occurrence of soil borne diseases and increase crop yield.In order to clarify the effects of different soil amendments on soil microbial community structure and diversity，a pot experiment was conducted to compare the improvement effects of quicklime(S1)，amino acid ecological fertilizer(S2)and fulvic acid water-soluble fertilizer(S3)on the microbial community structure of acidified soil.The results showed that the richness and diversity of soil bacteria were decreased after the application of three soil conditioners，while the species richness of fungal community had no significant change.The dominant phylum of the improved soil was the same as that before the improvement，but there were great differences in the dominant genus.Iamia and Peroneutypa were the unique dominant genera of S1，and Arthrobacter，Debaryomyces and Paraphaeosphaeria were the unique dominant genera of S2.Rhizopus and Schizophyllum were the unique dominant genera of S3.Among the improved soils，S1 had the strongest screening effect on bacteria，S2 had the greatest impact on fungal community，and the number of genus that relative abundance increased the most was in S3.The three soil amendments all could inhibit the growth and colonization of harmful soil microorganisms，but the inhibition mechanism might be different.In conclusion，the three soil amendments can optimize the microbial community structure of acidified soil，but the optimization effects are different.The results of this study can provide a theoretical basis for the further study of microbial function in improved soil and the control of soil borne diseases.