The invention relates to a Zaoxiang pomelo 
magnesium deficiency 
repair method. The method comprises the following steps that 1, one-time basal application is conducted before 
germination of Zaoxiang pomelos, wherein basal application includes three-
nutrient compound 
fertilizer and 
magnesium containing 
fertilizer; 2, leaf sample collecting and content measurement are conducted, wherein leaf samplesare collected, and the 
chlorophyll content and element content of the leaf samples are measured; 3, fruit sample collecting and 
quality measurement are conducted, wherein fruit samples are collected,and the total 
sugar content, soluble 
solid content, 
total acid content, Vc content, juice yield and edible rate of the fruit samples are measured; 4, data denoising is conducted; 5, 
fertilizer supplementing is conducted, wherein according to the determined element content and fruit 
quality data, whether or not the 
magnesium content reaches a good value is judged, and whether or not magnesium fertilizer needs to be supplemented is determined. The method has the advantages that leaf yellowing, winter old 
leaf fall off and too small fruits which are caused by 
magnesium deficiency can be effectively treated; the magnesium content of a Zaoxiang 
pomelo tree body is increased; the single 
fruit weight, yield and quality of the Zaoxiang pomelos can be significantly improved, and the appropriatelyapplied magnesium fertilizer types and the magnesium fertilizer and medium and micro 
nutrient element combining application technology are provided.