A mixed analog-to-digital converter circuit capable of stabilizing voltages at two ends of a load and reducing output voltage ripples, includes a power supply, a digital converter, an analog converter, and a load assembly. The analog converter includes power supply capacitors arranged in parallel; and when working, the load assembly is connected to corresponding power supply capacitors, and the power supply capacitors not connected to the load assembly are connected to the digital converter. The digital converter includes a component multiplexer connected to input and output ends of a power supply through wires; the component multiplexer includes power supply capacitors arranged in series; the analog converter includes the component multiplexer; two ends of each power supply capacitor in the component multiplexer are respectively connected to input and output ends of the load assembly through discharge wires; and when working, the load assembly is connected to corresponding power supply capacitors.