Currently, because of poor knowledge and the aim of profit, the use of chemical fertilizers, plant protection chemicals, pesticides, and herbicides and the wastes of manufactories, industrials zones have caused the pollution of soil, water, and air. Thus, vegetables may be contaminated by some heavy metals such as As, Hg, Sn, Cd, Cu, Zn..., which produce toxic substances ano harmful bacteria. Hence, the authors select the research: "Analysing content of lead in vegetables in Thai Nguyen city by photometric-extractive method". The authors have studied the effect complexing single LIGAN Pb-PAN, optimal codition for the complexation Pb2+-PAN, determine the composition of complex Pb-PAN, examined the effect of some metal ion to the chelating, building a standard curve with the presence of ion under the in fluence of their content. From to these results, the authors have determined the amount Lead content min the 15 samples of vegetables are lower than Vietnames standard (TCVN 46/2007), ie safe non-toxic.