The origin of ore is a key issue in bronze age archaeology. It has also been one of the most difficult studies. By comparing isotope ratios of lead found in ore beds and those from bronze, the researcher can sometimes identify the source and origin the bronzes. This study used the MAT - 262 thermal ionization mass spectrometry (TIMS) to detect the isotope ratios of lead contained in bronzes from the Lijiaba, Xiaotianxi, Daping and Yujluhu sites in the Chongqing area. The results indicate that Pb in the bronze alloys is common lead, and that the ratios of 206 Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb are 17.46 -18.67, 15.56 -15.85 and 36.78 -39.39, respectively. Except for two data sets, all results have good overlap and fall within a narrow range, indicating the same origin of the lead material. Furthermore, the isotope ratios of lead contained in bronzes from the Chongqing area match those of Pb - Zn deposits in the Sichuan - Yunnan - Guizhou Pb - Zn mineralization district, with the results being especially close to those isotope ratios of Disu and Daliangzi Pb - Zn deposits. The results suggest that lead ore used for bronze in Chongqing during the East Zhou period came continuously from the same location. The results also suggest that the bronze smelting site of the Ba people is independent from that used from the early Spring and Autumn Period to the Warring Period.