The invention relates to a method for preparing Malus spectabilis alkaloid, and relative application, comprising that using Malus spectabilis extractive to immerge paste powder, adding acetic acid ethyl ester, chloroform or butanol to reflux or immerge for several times, until the extractive has not alkaloid reaction, extracting via acetic acid ethyl ester, chloroform or butanol for several times, until the water phase has not alkaloid reacton, taking the organic extractive liquid, concentrating and recycling solvent, to obtain the Malus spectabilis alkaloid compound, or using Malus spectabilis extractive to immerge paste powder, adding silica gel to be mixed uniformly to obtain material gel, penetrating in penetrating barrel via chloroform, until the penetrated liquid has no alkaloid reaction, washing the filter liquid via acid water, extracting via acetic acid ethyl ester, depressurizing, concentrating solvent, to obtain the final product. The inventive compound can be used to treat rheumatic arthritis, atrophic arthritis, Cazenave's lupus or the immunologic rejection after organ transplantation.