Advanced glycation end products(AGEs) are largly involved in the pathogenesis of diabetic nephropathy. It is obvious that inhibition of AGEs formation is important in preventing the occurrence and progression of diabetic nephropathy. In diabetes, this reaction is greatly accerated and is important in the pathogenesis of diabetic complications, especially diabetic nephropathy. Therefore, to seek possible AGEs inhibitors in herbal medicines, unprocessed - and processed Magnolia Bark were examined in vitro as basic data for aniaml experiment. The content of magnolol in unprocessed Magnolia Bark was $0.796{pm}0.072%$, and after processing was decreased to $0.586{pm}0.101%(p<0.01)$. The content of AGEs was measured by their intrinsic fluorescence. The $IC_{50}({mu}g/ml)$ values of aminoguanidine, unprocessed- and procesled Magnolia Bark are $38.845{pm}8.36{mu}g/ml$, $54.264{pm}3.153{mu}g/ml$ and $27.882{pm}1.836{mu}g/ml$, respectively. This result means that prcessed Magnolia Bark was more effective than aminoguanidine, as positive control.