Design rules for liquid crystal (LC) lens with low driving voltage are studied in this paper. Many rules are obtained from simulations of five kinds of LC materials. If normalized Δneff of the LC material is less than 95%, the driving voltage of LC lens will be less than 10 V. On the premise that the performance of LC lens is satisfied and fabrication process is permitted, the smaller the normalized Δneff, the lower the driving voltage of the designed LC lensis. The results in can guide people in this paper designing and preparing the LC lens with high performance.