The effects of special formula fertilizer decrement application combined with planting smooth vetch on citrus fruit yield and quality，nutrient concentration and utilization were analyzed，aiming to decrease application of chemical fertilizer，and improve fruit quality and yield，nutrient efficiency for sustainable citrus production.Field experiments were conducted with 7-year-old Lane late navel orange orchard in Zigui and 28-year-old Satsuma orange orchard in Yiling，Yichang，Hubei，China.Four treatments，local conventional fertilizer(CK)，citrus special formula fertilizer with the same total NPK amount as conventional(DL)，citrus special formula fertilizer with 25% decrement of the conventional(JL)，and citrus special formula fertilizer with 25% decrement and planting smooth vetch(JLL)，were designed with four replicates per treatment and 3～4 consistent growing trees in each plot.The concentrations of N，P，K in plant and soil，fruit yield and quality were measured by conventional methods.The results showed that:1)Applying citrus special formula fertilizers as same or even 25% decrement of total NPK amount as local conventional fertilizers did not reduce fruit yield of Lane late navel orange and Satsuma mandarin orange；while citrus fruit yield was raised by combined 25% decrement application of citrus special formula fertilizer with planting smooth vetch.2)The N，P，K fertilizer efficiency was evaluated by citrus fruit yield(kg)per kilogram NPK nutrient amount，and it was raised by the citrus special formula fertilizer application with the same or even 25% decrement of total NPK amount as local conventional fertilization，especially by combined citrus special formula fertilizer application as 25% reduction total NPK as conventional with planting smooth vetch of Satsuma mandarin orange.3)The fruit quality indexes of Lane late navel orange and Satsuma orange were improved by citrus special formula fertilizer application with the same or even 25% decrement of total NPK amount as conventional fertilization，and particularly by combined citrus special formula fertilizer application as 25% decrement of the conventional with planting smooth vetch，such as the fruit soluble solids，Vitamin C content and solid-acid ratio，but the titratable acid content was declined.4)Planting smooth vetch with 25% reduction application of citrus special formula fertilizer raised the nitrogen and phosphorus concentrations of spring shoot leaves of Lane late navel orange，but decreased the topsoil available nitrogen and phosphorus contents in May and available nutrients concentrations of 20～40 cm soil for two tested orchards，with no significant effects on topsoil available N，P，K in later seasons.The fruit quality and fertilizer N，P，K efficiency were improved by citrus special formula fertilizer application，while combined planting smooth vetch with 25% decrement application of citrus special formula fertilizer improved fruit yield and quality，fertilizer efficiency of Lane late navel orange and Satsuma mandarin orange.