Abstract: To address the problems of current realistic glare rendering approaches, this paper presents a GPU based real-time method for rendering realistic glare.Firstly, the diffraction grating with random lens noise is efficiently generated according to lens aperture.Secondly, based on diffraction principle, a fast Fourier transformation algorithm with pre-computed coefficients is employed to simulate both Fraunhofer and Fresnel diffraction, and a spectrum model is used to achieve photorealistic rendering and two independent one-dimension Gaussian kernels are introduced to achieve bloom effect.Thirdly, we apply random small rotation operations and blend operations to enhance the photorealism.Finally, the glare effect can be added into a three-dimensional scene with the new glare rendering approach integrated into a real-time ray tracing framework.Our method is implemented on CUDA architecture and efficiently utilizes the powerful GPU parallel processing capability and memory hierarchy.Experimental results show that our method can achieve real-time performance and improve realism of scenes.