In this study,two individuals,GS-Y14 with high acid content and DS-Y182 with low acid content,from hybrid offspring of ‘Yali’בJingbaili’ were used to analyze the dynamic changes of organic acid and enzyme activities in pear fruit.The results showed that GS-Y14 belongs to malic acid dominant type,DS-Y182 belongs to the citric acid dominant type.The difference in total acid contents between DS-Y182 and GS-Y14 individual was mainly attributed to the content of malic acid during ripening.NADP-ME as key enzyme plays a decomposition role in malic acid pathway,and showed significant difference near ripening in two species,so the NADP-ME was the main reason leading to the difference of malic acid between GS-Y14 and DS-Y182,and effect the final acid accumulation in fruit during ripening.The increasing activity of PEPC favored the synthesis of citric acid.CS is the key enzyme in the change of malic acid content.In the early period,Cyt-ACO and Mit-ACO showed little effects on the change of citric acid content.In the later period,the activity of NAD-IDH enzyme has a certain effect on the citric acid accumulation in different progeny.