Abstract: 【Objective】 To explore the changes of pectin components and content in apricot fruit development and the influence on fruit hardness. 【Methods】 In this study, three apricot varieties, 'Kuqa White Apricot', 'Huntai white Apricot' and 'Shushu Dry Apricot', were selected as experimental materials.The relationship between the changes of pectin composition and content and the changes of fruit hardness was analyzed by measuring the growth quality indexes, pectin composition and content and the activity of pectin metabolizing enzyme during the development of apricot fruits. 【Results】 The results showed as follows: Compared with the other 4 growth stages, the fruit hardness of 3 apricot varieties decreased significantly at the ripening stage (P < 0.05).During fruit development and ripening, PME activity of the three apricot varieties showed a decreasing trend, and fruit hardness was significantly positively correlated with PME (P < 0.05), while fruit hardness was significantly negatively correlated with ion-bound pectin content and covalently bound pectin content (P < 0.01). 【Conclusion】 During fruit development, the fruit hardness of the three apricot varieties is negatively correlated with the content of ion-bound pectin and covalently bound pectin (P < 0.01), which has a great influence on the fruit hardness.Ionic pectin (ISP) has a small molecular weight and is easily soluble in water.The larger the ISP proportion in pectin, the softer the fruit texture.The decrease of hardness of ‘Luntai white apricot’ and ‘Shushanggan apricot’ was mainly caused by PG, while that of ‘Kuche white apricot’ was mainly causedy PL.The hardness of ‘Luntai white apricot’ decreased with the increase of PG activity since the hardcore stage.But in ‘Shushanggan apricot’, PG activity even decreases significantly after young fruit stage, increases significantly after turning color stage, and hardness decreases.The PG activity of ‘Luntai white apricot’ should be inhibited after the hardcore stage, and that of ‘Shushanggan apricot’ should be inhibited after the turning stage.The PL activity of ‘Kuche white apricot’ is always higher, and it needs to inhibit PL activity in pectin.