A liquid crystal (LC) lens includes a first substrate, a second substrate, and a plurality of liquid crystal units disposed between the first substrate and the second substrate. Each liquid crystal unit includes a first sub-unit having a first electrode and a second electrode disposed on the first substrate with a first interval therebetween and a third electrode and a fourth electrode disposed on the second substrate with a second interval therebetween. A first voltage difference is applied between the first electrode and the third electrode, and a second voltage difference is applied between the second electrode and the fourth electrode. The polarity of the first voltage difference is contrary to that of the second voltage difference, and the first interval is not equal to the second interval. A 3D display including the LC lens and a display panel is also provided.