K2NiF4 type compounds Sm2-xSrxCuO4 (0≤x≤ 1.2) were prepared. Rietveld refinement of powder diffraction data shows that the crystal system of these compounds belongs to T' type tetragonal structure of space group 14/mmm, and the addition of Sr causes a dramatic shift of the O(I) ions along the c axis from Sm (Sr) toward Cu while scarcely affecting the Cu-O (Ⅱ) bond in basal CuO4 plane. From XRD data, it can be seen that when 0.0≤ x≤0.6, Sm2-xSrxCuO4 belongs to a singlephase K2NiF4 type structure, while at x≥0.7, both the free SrO phase and the CuO phase exist in these compounds. From the results of XPS and Rietveld refinement, it can be seen that after replacing Sm3 + with Sr2 + of lower valence, the valence of Cu and Sm does not change apparently, and thus some defect must be formed at the oxygen ion positions and/or position A on A2BO4 to keep charge balance and to stabilize the structure.