A single ion imaging-based detection method and device are provided. After being reflected by an electromodulation singularity coupling differential imaging reaction unit, a probe beam from a total internal reflection ellipsometry imager converges on a CCD or CMOS detector, the acquired sensing surface image data is transmitted to a signal processing unit, the common mode noise is eliminated by performing spectral analysis on differential signals of a working sensing surface and a reference sensing surface, the peak intensity of a modulating signal is selected on the spectrum for wave filtering to obtain a real-time signal of interaction of single ions or charged molecules at a solid-liquid interface. Based on the singularity effect at a surface plasma resonance angle of an ellipsometry phase and a corresponding optical signal noise suppression scheme, the present application can achieve real-time observation of the adsorption of single ions or charged molecules at a solid surface.