Sequential injection lab-on-valve (LOV) was first proposed for analyzing ultra-trace amounts of Pb using differential pulse anodic stripping voltammetry (DPASV) with a miniaturized electrochemical flow cell fabricated in the LOV unit. Deposition and stripping processes took place between the renewable mercury film carbon paste electrode and sample solution, the peak current was employed as the basis of quantification. The mercury film displayed a long-term stability and reproducibility for at least 50 cycles before next renewal, the properties of integrated miniature LOV unit not only enhanced the automation of the analysis procedure but also declined sample/reagent consumption. Potential factors that affect the present procedure were investigated in detail, i.e., deposition potential, deposition time, electrode renewable procedure and the volume of sample solution. The practical applicability of the present procedure was demonstrated by determination of Pb in environmental water samples.