In order to reduce the error in copper analysis due to the volatilization of iodine and precipitation of CuI when the iodometric method is used for copper analysis, some improvements for the iodometric determination of Cu in copper ores are made through the experiments. The addition of polyvinyl alcohol improves solubility of CuI and prevents CuI from precipitation loss. And a stable complex of polyvinyl alcohol with I2 is formed, which prevents I2 from volatilization loss. Polyvinyl alcohol can also substitute starch as an indicator. The improved method provides the advantages of reliablity, simple operation and low cost.