To improve fertilizer efficiency and enhance yield and quality，the effects of nitrogen，phosphorus and potassium mixed fertilizer on the yield and index ingredients of Peucedanum praeruptorum Dunn were studied. A field experiment with three-factor and three-level orthogonal experimental design was conducted to study the effects of nitrogen (N 0，36.8，73.6 kg/hm²)，phosphorus (P2O5 0，24，48 kg/hm²) and potassium (K2O 0，41.6，83.2 kg/hm²) mixed fertilizer application on the yield and concentrations of praeruptorin A，praeruptorin B，extract，plant nutrients，rhizosphere soil nutrients of P. praeruptorum. The results showed that，compared with no fertilization，sufficient mixed fertilizer increased the concentration of rhizosphere soil available nutrients，accumulation of nitrogen，phosphorus，potassium nutrients in root，root biomass and concentrations of praeruptorin A，praeruptorin B，extract. The best quality of P. praeruptorum appeared at late December. At this period， three index ingredients reached the standard of the Chinese Pharmacopoeia (2020)under T5 treatment(N 36.8 kg/hm²，P2O5 48 kg/hm²，K2O 0 kg/hm²)，the biomass of which was 32.54 g/plant，increase of 49.95% compared to no fertilization. Less nitrogen and more phosphorus fertilizer application can improve yield and quality of P. praeruptorum when potassium is adequate in soil. The suitable harvest period is at late December. In this study，optimal nitrogen and phosphorus mixed fertilizer application were 36.8 and 48 kg/hm²，respectively.