Forthe rapid detection of heavy mental ion concentration in water, a protable detection instrument was designed based on electrochemical analysis.The STM32 micrcocontroller was adopted as control kernel, combined with peripheral circuits such as the scanning voltage generating circuit, the potentiostat circuit and micro current detecting unit. And the last two, regarded as core hardware circuits of the system, were analyzed in detail and tested.The results showed that the hardware circuits operated well and the equipment was stable and reliable. Screen-printed electrodes modified by bismuth-film coupled with differentialpulseanodicstrippingvoltammetry (DPASV) provideddeterminate experiment of the concentration of cadmium ion and lead ion in solution, and the stripping voltammetry curves are acquired. Experimental results showed that stropping peak current and heavy mental ion concentration had satisfactory linearity and repeatability, and the linear correlation coefficient of cadmium ion and lead ion reached to 0.9945 and 0.9978 respectively. Compared with atomic absorption spectroscopy (AAS), the maximum relative error is 4.93%,it showed that the instrument was accurate.