Abstract: 【Objective】 To investigate the correlation between apple fruit morulae and changes in quality and enzyme activities.【Method】 Quality,enzyme activity and correlation with flesh development were analyzed at different development stages of Marshal variety Tianwang 1,and the main enzymes and quality indices affecting flesh development were investigated and analyzed.【Result】 With increasing fruit maturity,the firmness,water content and titratable acid content of the pulp decreased significantly,while the soluble sugar content increased significantly; the content of soluble solids and VC first increased and then decreased. The activities of malondialdehyde（MDA）,polygalacturonase（PG） and amylase（AM） in the fruit changed from "up down up" with the development of the fruit,β-galactosidase（β-Gal） and cellulase（Cx）showed an "up down" trend,while pectin methylesterase（PME） increased significantly. Under cold storage（4 ℃）,the soluble sugar content of apple fruit increased significantly with the prolongation of the storage period; the contents of water,soluble solids,titratable acid and VC decreased significantly,and the firmness of the pulp decreased significantly after 60 days of cold storage. The activities of PG,AM and PME in fruit increased significantly with storage,while the activities of Cx decreased significantly,MDA and β-Gal activity changed little. Fruit firmness and water content were significantly negatively correlated with PME,PG and AM β-Gal is highly significant or significantly negative correlation,MDA is significantly negative correlation and Cx is highly significant or significantly positive correlation. The order of enzyme activities affecting fruit firmness and water content was PME＞AM＞PG＞Cx＞ β-Gal＞MDA and AM＞PME＞PG＞Cx＞ β-Gal＞MDA. The firmness and water content of the pulp were negatively correlated with soluble sugars,but positively correlated with VC and titratable acid.【Conclusion】 The main enzymes affecting fruit development in Marshall are PME,PG and AM; the quality indices affecting fruit development are flesh firmness and moisture,but VC,soluble sugar and titratable acid also affect the degree of fruit development.