Abstract: The effects of different concentrations of cyanamide on the biological characteristics and fruit quality of ‘one year two harvest system’ of ‘Summer Black’ grape were studied by using different concentrations of cyanamide（‘Rongya ’and ‘Yuguofeng’）.In order to provide a reference for the realization of ‘one year two harvest system’ of ‘Summer Black’ grape in Southern Xinjiang.The results showed that,compared with the control（CK）,different cyanamide treatments significantly reduced the internode length and diameter of new shoots,but had no significant effect on leaf length,half leaf width and chlorophyll SPAD value;it had no significant effect on the fruit shape index,maintained the appearance characteristics of ‘Summer Black’ grape,significantly increased the vertical and horizontal diameter of the fruit,significantly increased the single fruit weight and single panicle weight of the fruit,among which the single fruit weight of T1-T6 treatments increased by 27.98%,26.68%,25.62%,22.55%,14.52% and 9.80%,respectively,single panicle weight increase by 27.98%,26.66%,25.54%,22.57%,14.54%and 9.82%;significantly increased soluble solids content by 27.84%,25.85%,24.29%,24.29%,17.76%and 15.20%.In the range of treatment,there was no significant difference in biological characteristics and fruit quality among different concentrations of ‘Rongya’,the fruit quality of T4 treatment was significantly higher than that of T5 and T6 treatments,the fruit quality of ‘Rongya’ treatment was higher than that of ‘Yuguofeng’ treatment,which was significantly higher than that of T5 and T6 treatments.Comprehensive comparison showed that,the application of cyanamide in a certain concentration range could improve the fruit quality,in order to realize ‘one year two harvest system’ of ‘Summer Black’ grape in solar greenhouse in Southern Xinjiang,the effect of ‘Rongya’ treatments（20-40 times） was better.