The bromo-Qinghaosu (C17H27O5Br) crystal belongs to the monoclinic system, space group is P21, with a = 10.341?, 6 = 9.160?, c = 9.353?, β = 90°, Z = 2. The intensity data were collected on the Philips PW-1100 diffraetometer. Initial positional parameters (for double solution) were determined by a Patterson method. There are two heavy atoms bromine in the unit cell, it is centrosymmetric, that raises the problem of ambiguity. We have obtained a set of unique solution by means of chemical knowledge and direet method, respectively. Absolute configuration of molecule was determined by anomalous scattering method. Atoms coordinate parameters, ratio factor, isotropic and anisotropic temperature factors were refined by full-matrix least square method.