A kind of mesoporous SiO2 was synthesized using cationic surfactant as the structure-directing template. After that, the resulting mesoporous SiO2 was used to modify the carbon paste electrode (CPE). The electrochemical behaviors of honokiol and magnolol were examined. In pH 6.5 phosphate buffer, two well-shaped oxidation peaks at 0.31 and 0.44 V were observed at the mesoporous SiO2-modified CPE. Compared with the unmodified CPE, the mesoporous SiO2-modified CPE remarkably enhances the oxidation peak currents of honokiol and magnolol. This suggests that mesoporous SiO2 exhibits considerable surface enhancement effects to honokiol and magnolol. After optimizing the parameters such as pH value, amount of mesoporous SiO2, and accumulation time, a sensitive and simple electrochemical method was proposed for the simultaneous determination of honokiol and magnolol. As to honokiol, the calibration curve is from 2.0 to 100.0 A mu g L-1, and the limit of detection is 0.5 A mu g L-1 (1.8 x 10(-9) mol L-1). For magnolol, the linear range is from 20.0 to 200.0 A mu g L-1, and the limit of detection is 10.0 A mu g L-1 (3.8 x 10(-8) mol L-1). Finally, the newly proposed method was successfully employed to determine honokiol and magnolol in Chinese traditional medicines.