Single-shot terahertz time-domain spectroscopy (THz-TDS) leverages spatial encoding to rapidly measure terahertz (THz) waveforms, yet its application is limited by relatively low system precision. To address the issue that a detector’s detection accuracy is limited by its full-well capacity, this work elucidates the mechanism by which tuning the probe-light intensity suppresses the dominant noise source, namely the shot noise. Based on this mechanism, we designed a high-speed, high-precision sensor dedicated to single-shot THz detection. The sensor tolerates higher probe-light intensities without saturation, effectively reducing the relative contribution of shot noise and thereby significantly improving overall system precision. At a system repetition rate of 5 kHz, the minimum detectable terahertz field was measured to be 2.55×10-4 kV/cm kV/cm within one second. Compared with single-point detection, a 30-fold reduction in measurement time is achieved while maintaining the same information content. This work paves the way for further development of high-precision single-shot THz systems and rapid, complex, multi-dimensional THz spectroscopic experiments.