The cubic pyrochlore structure of Bi1. 5Zn1. 0Nb1. 5O7 was investigated. The crystal chemical formula of this material was determined as Bi1. 5Zn0.5 (Zn0.5Nb1.5) O7 by comparing the calculated theoretical X-ray diffraction intensities with the observed ones. Crystal structure parameters were refined by Rietveld method. The (Bi1.5 2yZn1 2yNb1.5) O7 y crystalline samples were also examined by Raman spectroscopy to look for further short range structural information. The results show that the Nb/O and Zn/O tretching modes in the B site oxide octahedral almost do not change with the chemical constitution changing. It is reasonable that the movable Zn2 is inclined to occupy B site first and then enter into A site after the B site was stuffed.