In order to solve the problem of soil fertility deterioration and fruit quality decline in Ningxia sandwatermelon， the effects of different quantity of bio-organic fertilize on quality and yield of watermelon were studied in field plot experiment using“Jincheng No. 5”as the experimentalmaterial.The results showed that when 3 750 kg·hm -2 bio-organic fertilizer wasapplied，the soil pH was8.39，the total salt content was 2.34 g·kg -1，which decreased 1.76% and26.18%，respectively， compared to CK in 0～20 cm soillayer.The distribution range of organic matter increased by12.99%，the content ofalkali nitrogen increased by56.06%，the content of available phosphorus increased 71.63% and the available potassiumincreased 28.78% compared withCK.The total nitrogen content of 0～ 20 cm soil layer increased by 176.84% and the totalphosphorus content increased by 92.53% compared withCK.With the improvement of soil physical and chemicalproperties，soil enzyme activity also showed increasing trend.The soluble solid content reached14.69%，which increased by 22.62%thanCK.The organic acid content was 0.051% and decreased by 41.38% compared withCK.The vitamin C content reached 12.74 mg·kg -1.The best application rate of bio -organic fertilizer was 3 750 kg·hm -2，which could decrease the continuouscropping obstacle ofwatermelon，and increase the activity of soilenzyme，yield and quality of sandwatermelon，meanwhileaccelerate the sustainable development of sand watermelon industry inNingxia.