An effective method for three-dimensional (3D) imaging with kinoform based on reflective phase-only Liquid Crystal Spatial Light Modulator (LC-SLM) was proposed. 3D image actually was reconstructed by the diffraction of kinoform using LC-SLM as a display unit. The calculation of kinoform, the relationships between parameters of LC-SLM with the kinoform, and some influencing factors in the quality of the reconstructed image were discussed in detail. In order to enhance the displaying resolution, a displayed object was decomposed into several sampling groups, and the corresponding kinoforms were calculated. When the kinoforms were inputted into LC-SLM successively within residual time of human eyes, the diffraction light wave may reconstruct the image of the original object, and then an observer can see a 3D image in free space. Experimental results demonstrate the correctness of the proposed approach, which provides an effective way for 3D display in practical application.