YBa₂Cu₃O_7-x superconductor was prepared by amorphous citrate process and the effects of pH and sin-tering termperature on transition temperature were examined. Kark blue transparent sol was obtained from the nitrate solution which has cation mole ratio of Y:Ba:Cu=1:2:3 and initial pH of the solution in the range of 5.5-6.5. YBa₂Cu₃O_7-x powders of nearly pure phase were prepared by sintering the citrate precursor in air atmosphere at 900℃ for 2 hours. In preparing YBa₂Cu₃O_7-x superconductor, it was found that pH has almost no influence on transi-tion temperature and that optimum sintering temperature was in the range from 900 to 950℃. Its sintering tempera-ture was in the range from 900 to 950℃. Its sintering temperature was between 94 to 97K. As the aberage copper valence and the content of oxygen were increased, the transition temperature was increased. The highest transition temperature attained at pH of 6.05 and sintering temperature of 950℃ was 97K. As basic work for manufacturing thin film of superconductor, the reactions between YBa₂Cu₃O_7-x and ZrO₂, SiO₂, γ-Al₂O₃, MgO were tested as substrate. Among them, MgO was not reacted with Ba in YBa₂Cu₃O_7-x.