A field experiment was carried out in Hainan to investigate the effects of applying MgSO4 in soil before flower period on the yield of mango and its quality，and the benefits and cost analysis was estimated thereafter.The experiment had three treatments:no fertilizer(CK)，farmers practice(FP)and applying magnesium fertilizer(Mg).The result showed that the yield was higher in the applying magnesium fertilizer treatment(12.06 t/hm2)，which increased by 9.7% than that of traditional fertilizers treatment.As compared with FP treatment，applying magnesium fertilizer increased the fruit total soluble solid and tssacid ratio by 9.6% and 28.1%，and reduced total titration acid by 14.6%，respectively.The net benefit of fruit production was the higher in the applying magnesium fertilizer treatment due to higher yield.In summary，mango applied with magnesium was economical viable which offers a new perspective for mango nutrients management.