An automatic monitoring system was developed for simultaneous determination of trace zinc, cadmium, lead, copper, iron and arsenic in environmental aqueous media using electrochemical stripping voltammetry. The sensor was mercury-film silver-based electrode. With a potentiostat, several pumps and valves controlled by computer, the system realized in-situ real-time detection of the six heavy metal ions mentioned above without manual operation. Quantitative heavy metals analysis at parts-per-billion level was performed by standard addition method. One measurement can be completed in 20 min with only 10 ml sample.