Huangkuangchang site in Dali, Yunnan Province is a large lead and silver production site of the Ming and Qing Dynasties. In previous studies, the mining age and total amount of silver tax at the site have been discussed, but further research is needed on the smelting technology used. This study reconstructed the lead and silver smelting technology of Huangkuangchang site by analyzing the smelting slags at four locations of this site. The results show that the slags from the various locations at Huangkuangchang site can be categorized into four groups—A, B, C and D, based on the differences in their morphological characteristics, major and trace elements, rare-earth element partition curves, and lead isotopic ratios. A, B and C slags were smelted using roasting-smelting, while the D slag was smelted using the iron reduction process. The lead isotopic analysis results show similar lead isotopic signatures for the ores corresponding to B and C slags, while the D slag has significantly higher lead isotope ratios. The analysis results of rare earth elements show that δEu of the B slag is negatively anomalous, while those of the other groups are slightly positively anomalous. For the A slag, one piece contains highly radioactive lead but the rest are similar to B and C slags, and the trace element content is more discrete while the distribution range is much larger than those of other groups, showing a more diversified source of silver-lead minerals. In summary, workers at Huangkuangchang site may have used a variety of processes for smelting, and lead minerals used may have come from a variety of different deposits, suggesting that the site underwent a number of changes in production techniques and resources over its long production period.