The yellowing of blood orange leaves is mainly due to the weak root growth, which can not absorb enough nutrients to meet the needs of plant growth and development. It is necessary to deeply apply organic fertilizer, improve the soil, make the soil layer deep, loose, fertile and deep-rooted, cultivate developed root groups, enhance the ability to absorb nutrients, and provide sufficient and comprehensive nutrients for the growth and development of the aboveground parts, so that the aboveground parts can flourish and the leaves are dark green, and there is no yellowing of the leaves. In addition, it is necessary to strengthen fertilization management, apply nitrogen, phosphorus and potassium (20~20~20) water-soluble fertilizers to roots in time, and spray the mixed solution of magnesium sulfate, zinc sulfate, urea, potassium dihydrogen phosphate and amino acid active liquid fertilizer to leaves every 7~ 10 day for 2~3 times to improve the plant nutrition level and promote the growth of trees.