The liquid crystal spatial light modulators (LC-SLM) are recently emerging as wavefront aberration correctors for use in low cost adaptive optics system (AO). As a novel aberration corrector，the wavefront generation performance of a phase-only LC-SLM is a governing factor that determines its ability for wave-front correction in an AO system. In this article，the performance of wave-front generation of LC-SLM is demonstrated by the production and quantification of the first 36 Zernike terms with different values. The factors，such as the fill factor，fringe field effect，pixel structure，the phase wrapping method and different phase strokes to impact wave-front generation are analyzed.