Abstract: 【 Objective 】 To explore the regularity of ethylene synthesis in the development of Xinjiang apricots in the hope of providing theoretical basis for the regulation of ethylene on the ripening mechanism of apricot fruits. 【 Methods 】 In this study, 3 cultivar apricots: Luntaibaixing, Kuchebaixing and Kumaiti were taken as research materials to test some indicators, such as ethylene release, respiration rate, ethylene synthetic precursor substance content, enzyme activity associated with ethylene synthesis, fruit hardness and fruit soluble solids content. And also, the variation of ethylene synthesis and its influence on fruit ripening index in Xinjiang were analyzed and compared. 【 Results 】 After flowering 42-56 d, the 3 cultivar apricots produced a little ethylene in system Ⅰ, and on the self-catalysis basis, after flowering 63 and 77 d, the 3 cultivar apricots produced a large number of ethylene in system Ⅱ. In the mature stage the ethylene release of 'Luntaibaixing' was significantly higher than that of the other two cultivars (P<0.05), and the time of a little of ethylene produced was earlier than the other two cultivars. During the stage of fruit development and ripening, the respiration rate showed a bimodal curve, and the fruit hardness decreased significantly with the increase of ethylene, among which the hardness of Luntaibaixing' decreased more significantly than that of the other two cultivars, and the soluble solid content increased significantly. The fruit soluble solids content of 3 cultivar apricots fruits showed an increasing trend. The changes of related enzyme activities showed a trend of gradual increase after flowering 49 days. There were significant differences in enzyme activity and precursor content among different apricot cultivars (P<0.05). The correlation analysis of the three cultivars of apricot showed that there was significant correlation between ethylene and enzyme activity and the content of precursor metabolites. 【 Conclusion 】 The regularity of ethylene synthesis and the contents of precursor substances in the whole development and ripening stage of Xinjiang apricot are divided into two stages. The increasing activity of related enzymes in the development of apricot fruits coincided with the increasing ethylene release. The synthesis of ethylene decreased the hardness, increased the soluble solid content and respiratory jump occurred to regulate fruit ripening.