Abstract: 【Objective】 To simplify fertilization and study the effect of long-acting fertilizer on the growth,yield and quality of muskmelon under the conditions of protected cultivation in Hainan. 【Methods】 With the melon "Nasmi" as the test material,the experiment set up 5 treatments including no fertilization(CK),long-term fertilizer(K₁),long-term fertilizer(K₂),long-term fertilizer(K₃) and conventional fertilizer(CF).Under the condition of protected cultivation,the long-acting fertilizer of Prolete(17-17-17) ≥ 51% was applied to investigate the agronomic growth index of crops at the melon extension stage,flowering and fruit stage and mature stage,and then to measure the yield and quality of melon at the mature stage,and measure the soil nutrients and the nitrogen,phosphorus and potassium content of each organ of the plant. 【Results】 Among the five fertilization treatments,the yield and fruit cracking rate of CF treatment were higher than those of other treatments,and the quality of CF and K₁ treatment was higher than those of other treatments.The accumulation of nitrogen,phosphorus and potassium in muskmelon plants under different treatments of long-acting fertilizer was lower than those under CF treatment. 【Conclusion】 According to the yield,fruit cracking rate and quality characteristics,the treatment of long-acting fertilizer (K₁) can ensure the normal growth of muskmelon in the facility to achieve higher commercial yield and quality.