Liquid crystal on silicon (LCoS) plays important roles in display areas and various tunable photonic devices with the advantages of low cost,no moving parts,low power consumption and high reliability.With the development of integrated circuit production technology,the ultra-high resolution liquid crystal on silicon devices became possible to obtain excellent performance.In this talk,we will report some of our recent research on the performance of ultra-high resolution liquid crystal on silicon devices which used as LCoS displays and phase modulators.The fringing electric field effect is studied by accurate numerical modeling.The influence from adjacent pixel,cell thickness and pre-tilt angle is also investigated.