Abstract: Space target imaging simulation technology is an important tool for space target detection and identification, with advantages that include high flexibility and low cost. However, existing space target imaging simulation technologies are mostly based on target magnitudes for simulations, making it difficult to meet image simulation requirements for different signal-to-noise ratio (SNR) needs. Therefore, design of a simulation method that generates target image sequences with various SNRs based on the optical detection system parameters will be important for faint space target detection research. Addressing the SNR calculation issue in optical observation systems, this paper proposes a ground-based detection image SNR calculation method using the optical system parameters. This method calculates the SNR of an observed image precisely using radiative transfer theory, the optical system parameters, and the observation environment parameters. An SNR-based target sequence image simulation method for ground-based detection scenarios is proposed. This method calculates the imaging SNR using the optical system parameters and establishes a model for conversion between the target’s apparent magnitude and image grayscale values, thereby enabling generation of target sequence simulation images with corresponding SNRs for different system parameters. Experiments show that the SNR obtained using this calculation method has an average calculation error of <1 dB when compared with the theoretical SNR of the actual optical system. Additionally, the simulation images generated by the imaging simulation method show high consistency with real images, which meets the requirements of faint space target detection algorithm research and provides reliable data support for development of related technologies.