Targeting at the problem of unreasonable fertilization caused by unclear fertilizer dosage and optimal fertilization ratio in foxtail millet[Setaria italica(L.)P. Beauv.]production in northwest arid region of China，this paper，adopting the “3414” fertilization scheme，studied the effects of nitrogen，phosphorus and potassium on the foxtail millet’s growth and yield in northwest arid region of China through different combinations of nitrogen，phosphorus and potassium fertilizers and identified the optimal nitrogen，phosphorus and potassium fertilization ratio suitable for Loess Plateau in northwest arid region of China.The results showed that fertilization promoted the growth of foxtail millet，and the effect was the best when applied with the proper amount，in which the average number of roots，plant height and stem diameter of millet under the non-fertilization treatment(N0P0K0)were 44.1，113.9 cm and 8.75 mm，respectively，and that of fertilization treatment was higher，increased by 4.1%-73.0%，8.0%-19.1% and 3.2%-17.8%(P<0.05)，respectively.From the perspective of single fertilizer，the agronomic traits of millet did not increase gradually with the increase of nitrogen，phosphorus and potassium fertilizer dosage.The biomass of millet under low nitrogen (N1P2K2)，phosphorus (N2P1K2)and potassium (N2P2K1)fertilization was 23.4%，21.4% and 19.4% higher than that of millet without nitrogen(N0P2K2)，phosphorus(N2P0K2)and potassium(N2P2K0)fertilization，respectively(P<0.05).However，the biomass of the higher N，P and K treatment(N2P2K2)was lower than that of N1P2K2，N2P1K2 and N2P2K1 by 5.5%，4.1% and 4.0%，respectively(P<0.05)，demonstrating that appropriate nitrogen，phosphorus and potassium fertilizer was more beneficial to promote foxtail millet’s growth.During the growth process，foxtail millet showed the strongest dependency on nitrogen，reaching 14.9%，while the dependency on phosphorus was the weakest，at only 1.6%.When nitrogen，phosphorus and potassium were applied in combination，they exhibited the best fertilizer efficiency.This combined application effect，averaged over two years，even exceeded the effect of applying nitrogen fertilizer alone by 57.0%(P<0.05).The effect of nitrogen，phosphorus and potassium on foxtail millet’s yield was significant interactive(P<0.05).Low phosphorus(45 kg/hm²)and medium potassium(30 kg/hm²)were beneficial to nitrogen fertilizer efficiency，low nitrogen(75 kg/hm²)and medium potassium were beneficial to phosphorus fertilizer efficiency，and low nitrogen and medium phosphorus(90 kg/hm²)were beneficial to potassium fertilizer efficiency.According to the ternary quadratic regression equation of millet yield，the maximum yield of foxtail millet fertilization was N 103.7 kg/hm²，P2O5 96.4 kg/hm²，K2O 20.6 kg/hm².The usage of nitrogen and potassium fertilizers was lower than the conventional fertilization level(N 150 kg/hm²，K2O 30 kg/hm²).Therefore，with regard to control the amount of nitrogen and potassium fertilizer appropriately in the northwest arid region of China is of more significance for increase of the foxtail millet’s yield.