Three kinds of chromatographic columns were prepared by coating multi walled carbon nanotubes on the silica microspheres.To investigate retention behaviors of acidic，neutral and alkaline compounds，several kinds of aromatic compounds were used as target analytes.The separation conditions，such as ratios of methanol to water in mobile phase，column temperatures and flow rates were also investigated.In addition，the thermomechanical behaviors were discussed by calculating the thermodynamic parameters of enthalpy change，entropy change and gibbs free energy change in the process of separation.The result showed that the hydrophobicity of stationary phases was enhanced by coating carbon nanotubes.The retention mechanism was similar to reversed phase chromatographic column during the separation of sulfanilic acid and uracil.For neutral compound，the retention value and column efficiency were improved effectively because of π-π conjugate effects of carbon nanotubes.The arrangements of analytes changed from disordered to orderd，because of the addition of carbon nanotubes enhanced the retention of analytes on stationary phase.Besides，the retention mechanisms of analytes on different chromatographic columns are not dominated by one single retention mechanism，but by various mechanisms in a coordinated way.These results suggest the importance and great potential of multi-walled carbon nanotubes coated silica microspheres as stationary phase in the applications of separation and solid-phase extraction.