The invention discloses a trace heavy metal detecting system based on a chronopotentiometric stripping analysis method. The trace heavy metal detecting system comprises a chronopotentiometric stripping analysis device and a screen printing electrode, wherein the chronopotentiometric stripping analysis device comprises a housing, a working main board positioned in the housing, an electrode insertion groove, a built-in power supply, an input unit and an output unit, the electrode insertion groove, the built-in power supply, the input unit and the output unit adopt the housing as the platform andare respectively arranged on the housing, the screen printing electrode comprises a substrate, the substrate is printed with a working electrode, a counter electrode and a reference electrode, the three electrodes are respectively covered with an insulating layer, one ends of the three electrodes form and the opening holes arranged on the insulating layers form an electrolytic cell cavity, a sample to be detected is added into the electrolytic cell cavity in a dropwise manner, the screen printing electrode is inserted into the electrode insertion groove of the housing, and the reference electrode joint is connected to the constant potential module of the working main board. According to the present invention, the detection system has characteristics of simple composition and easy miniaturization, and is matched to the screen printing electrode, such that the electrode pretreatment is avoided, and the use is convenient.