Liquid crystal on silicon (LCoS) can be devised as a pure phase type spatial light modulator (SLM) with proper arrangement of incident light polarization and choice of liquid crystal mode. The applications include digital holography, optical switching and adaptive optics etc. The phase retardation at each pixel on the LCoS SLM can be controlled by driving voltage, but the relationship is dependent of temperature and wavelength. In this paper, a vertical aligned nematics (VAN) mode LCoS has been used for investigation. Consideration the application environment, temperature range was set in between 30 to 70°, and the selected wavelength was 623 nm, 526 nm and 462 nm. We measured the E-O curve and converted into phase shift by equation. The result shows that the phase retardation decreases with both the increase of temperature and wavelength. The dynamic behavior of LC material is also reported in this paper, and a digital hologram from a digital-drive LCoS SLM with 6.4 μm pixel is demonstrated.