Abstract: The electronic noise of X-ray flat panel detectors (FPDs) significantly affects their low-dose imaging quality; however, the assessment of such effects in conventional studies is relatively indirect and fails to accurately reflect the actual imaging characteristics. Based on the Poisson distribution of quantum numbers, this study quantitatively analyzes the regulatory mechanism of electronic noise on the image signal-to-noise ratio (SNR) in the full dynamic range, particularly under low-dose conditions, with detector sensitivity and noise-equivalent electrons as input parameters. Experiments were performed using a Complementary Metal Oxide Semiconductor(CMOS) flat panel detector under simulated clinical low-dose radiation (RQA-5) conditions to verify the model. The results show that the SNR predicted by the model is highly consistent with the experimental data (with excellent goodness-of-fit). The results indicate that at a dose of 10nGy, the image SNR of the X-ray FPD with electronic noise optimized to 130e⁻ is 11 dB higher than that of an FPD with 3200e⁻ of electronic noise. Meanwhile, for the image-quality requirement of 10 dB SNR, the radiation dose required for the former detector is only one-seventh of that required for the latter. The abovementioned model provides a practical tool for the structural design and performance optimization of X-ray FPDs, which can effectively realize the accurate evaluation and optimization of low-dose imaging performance as well as provide theoretical support and a technical reference for the development of high-performance X-ray FPDs.