Abstract: DW-spectrophotometry with K coefficient method was applied to the simultanesous determination of 3 main flavonoids,namely rutin,quercetin and kaemferol,in Magnolia grandiflora L.The wavelength pairs selected for the measurements were 297 nm/293 nm for rutin,381 nm/397 nm for quercetin,and 428 nm/451 nm for kaempferol.Linearity ranges for determination of the 3 componental flavonoids were 0.635-12.7 mg·L-1,0.576-11.5 mg·L-1 and 0.456-9.12 mg·L-1 respectively.In application of the proposed method to analysis of a substantial sample,values of RSD′s (n=5) found were 0.1%,0.9% and 2.1% for the 3 respective flavones;Recovery tests were performed by standard addition method,giving average values of 103.0%,98.4% and 97.7%.