Effect of water soluble chitosan fertilizer application on the growth and yields of watermelon was studied by applying chitosan water soluble fertilizer in different ways and in different dosage in greenhouse.Two kinds of application methods were set with 4 level for each method.The eight treatments,were sprayed with water,sprayed with chitosan which be diluted 1 000 times,500 times and 250 times,drip irrigation water,drip irrigation 450 mL/hm2 every time,900 mL/hm2 every time and 1 800/hm2 every time.Every treatment was repeated three times.The results showed that after 35 days planting,chlorophyll,stem diameter,number of leaves and stem length of watermelon for the sprayed with chitosan treatments were significantly greater than those for spraying water treatment.The highest chlorophyll content and the maximum length of the main stem occurred in the treatment sprayed with chitosan diluted 250 times,with the value of 65.90 and 80.73 cm,respectively.After 50 days watermelon planting,there was no significant difference.Application of water soluble chitosan fertilizer could significantly increase the yield of watermelon,and spraying was better than drip irrigation.The highest yield of watermelon was 49 550 kg per hectare,which was drip irrigated 1 800 mL/hm2 every time water soluble chitosan.Whether spraying or drip irrigation,water soluble chitosan were able to significantly increase watermelon sugar content.According to the test results,the spraying pattern method was better than drip irrigation.In summary,the application of water soluble chitosan fertilizers could significantly improve the growing of watermelon,sugar content and yield,and spraying was recommended as the better method.