In order to improve the soil acidification of orange orchard and promote the sustainable development of orange orchard，the effects of shell powder of oyster on replacing lime on soil nutrients，citrus fruit quality and soil bacterial community were studied. The experiment adopted a single factor randomized block design，with four experimental treatments:100% lime，50% high calcium oyster shell powder + 50% lime，100% high calcium oyster shell powder，control group，represented by L，SL，S，CK，respectively. During the citrus ripening period，soil nutrients，fruit quality，and soil bacterial communities were sampled. Compared with CK，the treatments of L，SL and S significantly increased soil pH and soil available calcium content，and oyster powder treatment significantly increased soil available magnesium and soil organic matter content(P<0.05)；L，SL and S treatments significantly increased the edible rate，soluble solid content of citrus fruit and reduced the titratable acid content；S treatment with oyster shell powder also significantly increased the vitamin C content(P<0.05). In terms of soil microbial community，the relative abundance of Alphaproteobacteria and Bacillus was significantly higher than that of CK(P<0.05). PCoA showed that L treatment with lime had the greatest effect on the diversity of microbial communities in citrus soil. The application of calcin fertilizer significantly improved the soil pH，and then improved the soil acidity situation. Soil pH was an important environmental factor affecting the diversity of microbial communities，which significantly improved the relative abundance of Bacillus in the soil，and thus improved the soil microbial environment. After its increase can improve the soil microbial environment and significantly enhance the relative abundance of anti-bacteria. The application of oyster shell powder can better improve the quality of citrus and play a key role in its growth and development.