[Objective] This study aimed to investigate the improving effect of organic fertilizer on acidified soil as well as their effects on fruit quality and quantity in Yantai orchard.[Method] Plot experiment was conducted to investigate the effects of organic fertilizer on fruit yield and quality of Red Fuji and chemical properties of acidified soil.[Result] The apple yield in acidified soil applied with organic fertilizer all increased.Under the application of biological organic fertilizer,the apple yield was higher,and it was 8.92% higher than that in the control group.Under the mixed application of chemical fertilizer and biological organic fertilizer,the growth and development of apple trees were improved,and the total soluble solid(TSS) content,vitamin C(Vc) content and TSS-acid ratio in mature apples all increased.The application of organic fertilizer significantly reduced soil acidity.Compared with those in the control group,the soil p H value,organic matter content and alkali-hydrolyzable nitrogen content under the application of biological organic fertilizer were increased by 8.33%,15.10% and 30.80%,respectively.[Conclusion] The application of biological organic fertilizer could improve the yield of apple in acidified soil. [Objective] This study aimed to investigate the improving effect of organic fertilizer on acidified soil as well as their effects on fruit quality and quantity in Yantai orchard. [Method] Plot experiment was conducted to investigate the effects of organic fertilizer on fruit yield and quality of Red Fuji and chemical properties of acidified soil. [Result] The apple yield in acidified soil applied with organic fertilizer all increased .Under the application of biological organic fertilizer, the apple yield was higher, and it was 8.92% higher than that in the the control group. Unite the mixed application of chemical fertilizer and biological organic fertilizer, the growth and development of apple trees were improved, and the total soluble solid (TSS) content, vitamin C (Vc) content and TSS-acid ratio in mature apples all increased. The application of organic fertilizer significantly reduced soil acidity. Compared with those in the control group, the soil p H value, organic matter content and alkali-hydrol yzable nitrogen content under the application of biological organic fertilizer were increased by 8.33%, 15.10% and 30.80%, respectively. [Conclusion] The application of biological organic fertilizer could improve the yield of apple in acidified soil.