Abstract: To study the changes on the hardness and cell wall substances of loquat fruit,50-60 mg·L-1 exogenous ethylene gas was applied to treat 'Zaozhong No.6′loquat fruit.The fruits were preserved at low temperature after treatment and the microstructure analysis of pulp tissue was conducted.The results showed that exogenous ethylene treatment repressed the fruits in developing of hardness,decreasing of water-soluble pectin and fibering synthesis,but not affected total pectin in the fruits.After 20 days and 30 days preservation,hardness of fruits in treatment group increased by 35.9% and 57.8%,respectively,in contrast,that of control group increased by 62.5% and 90.0% respectively.40 days later,fruit hardness of two groups tended to be similar to each other.On the 40th day,the water-soluble pectin of fruits in treated group was 57.4% of that before the preservation,and in control group,it was 48.5% of that without preservation.The crude fiber content of fruits was 0.6 g·kg-1 more in control group than in treatment group.The observations of microscope on pulp cell microstructure agreed with the results.