Since the discovery of superconductivity in the La-Ba-Cu-O system, various compounds with high Tc have been investigated in a short time. However, phase diagrams have not been well-established except for the Y-Ba-Cu-O system. In particular, we can not obtained monophasic Pb-free "2223" phase in the Bi-Sr-Ca-Cu-O system at the present stage. In general, phase diagram study provides a basic knowledge on exploring of new compounds and elucidation of reaction processes. Thus, the phase diagram study for the Bi-Sr-Ca-Cu-O system is significant and indispensable to reveal the reaction process for the Pb-free "2223" phase. Phase diagrams for YO1.5-SrO-BaO-CuO system, BiO1.5-SrO-CaO-CuO system and LaO1.5-BaO-CuO system were reviewed based on our experimental results.