The present invention discloses a method of extracting and separating compounds which can inhibit NO production from medicinal plant Bulbophgllum radiatum Lindl, which including: preparing the extractof Bulbophgllum radiatum Lindl; separating the said extract with column chromatography and collecting the eluting components; concentrating the eluting components under reduced pressure to further theseparation and refine; analyzing the physical and chemical characteristic of the refined compounds to determine the molecular structures; assaying the NO inhibiting effect and the toxicity effect. An d it is found that the obtained compounds can inhibit NO production. Wherein the molecular structures of compound 1-3 are determined as above chart.