用Ｘ射线转靶衍射仪，详细地观察和分析了Ｂｉ２Ｓｒ２ＣａＣｕ２Ｏｙ单晶的调制结构．指出布喇格反射的卫星峰是沿ｃ拉长的，与Ｂ心正交对称结构不相符的宽化峰正是由于这种拉长的结果，且导致卫星峰强度的不对称性．ＢｉＯ层和钙钛矿层晶格失配形成的超晶格为非正交而是单斜的，并可能存在超晶格孪晶 The structure of Bi2Sr2CaCu2Oy single crystal was observed and analyzed in detail by X-ray diffraction. It is pointed out that the Bragg-reflected satellite peak is elongated along c , and the broadening peak that does not coincide with the symmetrical structure of center B of the B-axis is just the result of this elongation and leads to the asymmetry of the peak intensity of the satellite. The superlattices formed by the lattice mismatch between BiO and perovskite layers are nonorthogonal but monoclinic and may have superlattice twin