Effect of copper on potato tuber yield and some physiologibiochemical characters wasstudied.The experimental results showed that seed-tuber treatment by optimum concentration(0.01 %)of copper(CuSO4·5H2O)solution increased potato tuber yied(10.32-24.68%).Copper increased not only photosynthetic pigment contents in chloroplast,but nitrate reductase activity and some substance(soluble sugar and soluble protein)contents.