The chiral separation of the racemic mandelic acid ((R,S)-MA) by simulated moving bed chromatography with columns packed with Chiralcel-OD stationary phase is investigated experimentally and numerically. The transport dispersion model combined with the modified Langmuir isotherm was applied to predict the dynamic behaviour and separation performance of the SMB process. The Triangle Theory was used to obtain the complete separation region of the SMB operation. The influences of the switching time, loading, extract flow rate and column configuration on the SMB performance were also studied. The online monitoring system consisting of circular dichroism (CD) and UV detector in series was employed to measure the composition and purity of the extract and raffinate streams. Good agreement between the experimental data and model predictions proved the efficiency and reliability of SMB modelling and the Triangle theory in the design and operation of SMB chromatography. Experimental results show that purity and recovery at extract and raffinate port can reach 99% although not at the same time.