A capillary electrochromatography with covalent porous organic cage chiral material（CC3-R） was developed for the separation of mandelic acid.The single CC3-R with three dimensional diamond network channel was synthesized,and used as a chiral stationary phase to prepare a capillary electrochromatography column.The chiral recognition performance for CC3-R capillary electrochromatography column was investigated.The variations of current with voltage and electroosmotic flow with pH value of buffer solution were measured,and then this column was used to separate mandelic acid.Results showed that the baseline separations for D-mandelic acid and L-mandelic acid were obtained with the degree of separation of 1.81,and the numbers of theoretical tray for them both were 36 700 N/m and 41 600 N/m,respectively.The retention time of mandelic acid on the same CC3-R capillary column was observed with the relative standard deviation of 1.2%.Results showed that the CC3-R chiral column not only has a good chiral recognition ability,but also has good stability and reproducibility.