A new dibenzofuran derivative, 1,2,4-trimethoxydibenzofuran-3,9-diol (7), was isolated from the ethyl acetate fraction of Sorbus commixta barks, along with six known compounds, lupeol (1), betulin (2), betulinic acid (3), ursolic acid (4), -sitosterol (5) and -pyrufuran (6). Their structures were determined by NMR spectroscopic analysis, including of 1 H and 13 C NMR, 1 H-1 H COSY, HSQC and HMBC spectra data. Cytotoxic activities of seven compounds were evaluated in five cancer cell lines, HEp-2, A549, MCF-7, PC-3 and SKOV-3 at the concentrations ranging from 10 to 100 M.