Four chemical compounds,such as diosmin(Ⅰ), 5,8,4′-trihydroxy-6,7-dimethoxyflavone(Ⅱ), 5,7,3′-trihydroxy-4′-methoxyflavone(Ⅲ), octacosanoic acid(Ⅳ), are isolated from draff of above-ground part of Mentha haplocalyx Briq. after extracting volatile oil by silica gel and sephadex LH-20 column chromatography methods, and the structures of these compounds are elucidated by 1H-NMR,13C-NMR and ESI-MS. The compounds of Ⅰ,Ⅱand Ⅲ are firstly isolated from draff of M. haplocalyx.