Abstract: difference and their activities decreased again when fruit maturation. The levels of invertase and SS-cleavage in fruit of‘Ninghaibai’were higher than those in‘Dahongpao’, especially the acid invertase in fruit of‘Ninghaibai’was much higher than that in ‘Dahongpao’ at the late stages of fruit development. Activity of SDH in fruit of‘Dahongpao’was slightly higher than that in‘Ninghaibai’. Difference in sugar accumulation between red flesh and white flesh fruit of loquat relate to sugar metabolism.Sugar content, activities of sucrose and sorbitol metabolizing enzymes were measured in developing fruit of white flesh loquat cultivar ‘Ninghaibai’ and red flesh cultivar ‘Dahongpao’. The results showed that sugar accumulation pattern in developing fruit of two cultivars were almost same. The sucrose contents were almost stable during fruit development, while sorbitol content decreased with fruit development. Fructose and glucose were the major sugars in fruits of these two loquat cultivars, about 90% of glucose and fructose was accumulated within three weeks during maturation. The activities of invertase, sucrose synthase（SS）-cleavage and sorbitol dehydrogenase（SDH）showed the same change pattern that decreased at the early stages of fruit development, then increased at the later stages of fruit maturation. The changes in activities of SS-synthetic direction and sucrose phosphate synthase（SPS）showed some

Key words: Eriobotrya japonica Lindl., sugar accumulation, sucrose metabolism, sorbitol metabolism