We studied the composition dependence of highTcphase Bi2Sr2Ca2Cu3Oxformation in Pb‐doped Bi system thin films. Films were prepared by rf magnetron sputtering using three targets and post‐annealed to synthesize superconducting films. In addition to a Bi‐Sr‐Ca‐Cu‐O target, PbO and CuO targets were used to dope sufficient Pb into the films and to optimize the Cu content. Although heavily Pb‐doped thin films form the highTcphase rapidly, they are multiphased and have poor morphology. The Cu content decreases slightly during sintering. Minimizing the amount of doped Pb needed for the highTcphase formation improves morphology, and slightly Cu‐rich composition is effective in forming the highTcphase. Nearly single‐phase highTcfilms were obtained from the as‐deposited compositions of Bi:Pb:Sr:Ca:Cu=1.02:0.80:1.00:0.99:1.64 after only one hour of sintering in air at 851 °C. The single‐phase highTcfilm forms in a very narrow sintering temperature range.