To establish a method research the parameters of serum pharmacochemistry of Magnolia Officinalis. Based on the established HPLC fingerprint of Magnolia Officinalis, analysis and comparison were made between the HPLC fingerprints of rat serum samples obtained after orally taking extract fractions of Magnolia Officinalis and those of control rat serum samples. Three compounds were detected after oral administration of Magnolia Officinalis, two of which are Magnolol and Honokiol. These three compounds absorbed into blood are capable of being the effective constituents of Magnolia Officinalis. Further studies on them will help clarify the bioactive constituents and mechanisms of Magnolia Officinalis.