In this experiment，the cultivation method of nutrient solution hydroponic culture was adopted，and the South China cucumber material“9930”was taken as the research object. On the day when the female flower of the cucumber plant wasopened(recorded as 0day)，the cucumber plants were treated with three different nitrogen supplylevels(CK 12mmol/L，T1 0mmol/L，T2 3 mmol/L). The changes in AsA content and soluble sugar content in cucumber during short -term low-nitrogen treatment were studied. The results showed that the contents of T-AsA and AsA in fruit increased by 69.5% and 24% in the low-nitrogentreatments(T1 andT2)comparing with thecontrol，and the contents of T -AsA and AsA in leaf increased by 22.4% and20.7%，respectively. The contents ofglucose，fructose and galactose increased in the leaf and fruit especially thecontent of glucose and fructose increasedsignificantly，the content of xylose in the treated fruit decreased. On the third dayof treatment，the sugar content in cucumber fruit reached the maximum，increased by 200%. The results showed that short -term low-nitrogen treatment can increase the content of AsA and soluble sugar incucumber，which is beneficial to improve fruit quality.