Due to factors such as geographical position, sun and atmospheric environment, it is impossible to obtain the real images of space targets under various postures and illumination conditions, let alone under the interaction between laser, sun and background light. In this paper, a real-time target image generation method under multi-light source irradiation is proposed. This method is based on the modern graphics card programming technique and frame caching object advantages. At the GPU (Graphics Processing Unit) side, shader language is used to efficiently calculate target brightness values and enhance realism under the influence of multi-light source. The open-source 3D graphics engine named OSG (Open Scene Graph) helps support 3D model files of various formats and improve the compatibility with the domestic Kirin operating system as well as common battlefield situation display software. Simulation experiments demonstrate the effectiveness and superiority of the proposed method.