The optimized fertilization of nitrogen，phosphorus and potassium，and as well combined with calcium and magnesium，were evaluated to explore their effects on Guanxi pomelo，and contribution of reducing fertilization to carbon emission.It could provide the scientific basis for green fertilization technology to improve the quality and efficiency of Guanxi pomelo.Six experimental sites were arranged in Banzai Town，Pinghe County，the main producing area of pomelo，and three treatments were set up for each site，including farmers conventional fertilization (FFP)，optimized fertilization (OPT，with reduction of nitngen，phosphorus and potassium fertilizer)，and optimized fertilization in combination with calcium and magnesium fertilizers(OPT+Ca Mg).The effects of different fertilizer treatments on yield，quality，partial factor productivity of fertilizers，economic efficiency and the regulation effect of carbon emissions were studied.The results showed that:①Compared with FFP treatments，the yields of OPT and OPT+Ca Mg treatments did not decrease although fertilizer application was reduced，and the titratable acid contents of pomelo in OPT+Ca Mg treatment decreased by 7.0% and the solid-acid ratio increased by 8.8%.In contrast，There were significant differences in soluble solid content in some test sites，but there was no significant difference in the average soluble solid content，and there was no significant difference in the edibile rate of pomelo among all treatments. ②Compared with FFP treatments，the OPT and OPT+Ca Mg treatments significantly increased the partial productivity of nitrogen，phosphorus and potassium fertilizer for pomelo by 100.3%，130.6%，115.9% and 105.1%，135.6%，120.2%，respectively.③Compared with FFP treatments，the input cost of fertilizer and other agricultural materials for OPT and OPT+Ca Mg decreased by 13 and 11 thousand yuan per hectare (decreased by 25.3% and 20.7%)，and the profit per hectare increased by 27.4 and 32.3 thousand yuan (increased by 28.2% and 33.3%)，respectively. ④Compared with FFP treatments，the total carbon emission，net carbon emission per unit area and carbon footprint of pomelo plantations treated with OPT and OPT+Ca Mg were significantly lower than those treated with FFP，their reductions were 27.0% and 23.9%，39.0% and 34.0%，45.0 and 44.0%，respectively.In conclusion，the reduced input of nitrogen，phosphorus and potassium fertilizers and adding calcium and magnesium fertilizer are the effective measure to improve the quality and efficiency of pomelo production，which can significantly improve pomelo efficiency and utilization rate of fertilizer，reduce greenhouse gas emissions.