The present invention provides a liquid crystal lens and a 3D display device. By utilizing the metal wire grid (20) to realize the functions of electrode and polarizer at the same time, and the polarizer filters the o light to solve the display degradation issue due to the o light leakage, and corresponding high quality 3D image display is realized. By combining function of the polarizer and the electrode in the metal wire grid (20), the additional polarizer adhesion is no longer required, which can effectively decrease the thickness of the liquid crystal lens. The present invention further provides a 3D display device, which can decrease the thickness of the 3D display device to realize the high quality 3D image display.