In the bistable chiral splay nematic (BCSN) mode, the splay and p twist states are used for the two stable states. The transition between the memory states accompanies the motion of the disclination line, due to the topologically inequivalent from each other. The switching time is consistently coupled with the propagation velocity of the disclination line, which strongly depends on the amplitude of the applied voltage. In this paper, we demonstrate the gray scale of BCSN liquid crystal display (LCD) by the control of the domain density of the splay and twist states during the transition process.