To reduce the trailing phenomena for moving images in a Flat Panel Display(FPD), a grayscale control algorithm which simulates Cathode Ray Tube(CRT) grayscale rendition process is proposed. Firstly, the basic concept of FPD is introduced and the current major technology of reducing trailing, Black Frame Insertion Technology, is explained.Then, the reasons of trailing phenomena from moving images are introduced and the work processes of human eyes when moving images are displayed on CRT and FPD are illuminated and the grayscale rendition of a pixel is obtained. Furthermore, based on algorithm derivation, the algorithm realization steps and compared experiment results of traditional and proposed FPD grayscale control algorithms are discussed. Finally, the main program implemented with Very-High-Speed Integrated Circuit Hardware Description Language(VHDL) is presented and the specific rendition process is described. Experimental results indicate that the image quality is evidently improved and the trailing phenomena have been reduced to nearly 90% when the moving images are displayed by the FPD.The result meets the eye reflection mechanism.Moreover,the algorithm has advantages in less operation and storagy space and is easy to be implemented by hardware.