The watermelon ‘Heimeiren’ was used as material, applying the cassava starch anaerobic fermentation liquid (the chemical oxygen consumption was 1 200 mg/L, 150 t/hm2) to study the effects of cassava starch anaerobic fermentation liquid on growth, yield and quality of watermelon. The results showed that the treatment of applying the cassava starch anaerobic fermentation liquid treatment’s growth of lateral vine length, lateral vine thickness, lateral internode length, the fruit setting number, the single fruit weight and the yield were 64.4%, 51.6%, 13.5%, 20.9%, 16.8%, 61.9%, 72.7% and 105.8% higher than those of the general chemical fertilizer treatment, respectively. There was no significant difference in the first melon position between the two treatments; The longitudinal diameter, transverse diameter, fruit shape index, vertical diameter perimeter and horizontal diameter perimeter of watermelon fruit of applying the cassava starch anaerobic fermentation liquid treatment were 35.2%, 20.9%, 9.4%, 26.4% and 30.0% respectively, which were significantly higher than those of the general chemical fertilizer treatment. The contents of soluble solids, soluble sugar, soluble protein, vitamin C and titratable acid were 34.2%, 58.8%, 14.3%, 26.8% and 50.0% respectively, which were significantly higher than those of the general chemical fertilizer treatment, but there were no significant difference in the edible rate between the two treatments. Therefore, cassava starch anaerobic fermentation liquid can be used as additional fertilizer in watermelon production.