Lithium niobate (LiNbO3, LN) is a kind of multi-functional uniaxial ferroelectric material, and is widely used in optical modulators, optical frequency combs, optical waveguides, and so on. The emergence of conductive domain wall (DW), serving as a nanoscale conductive path embedded in the insulating materials and showing important application prospects in non-volatile memristor, logic gate, and transistor, etc., promoted the application of LN in the field of nano-opto-electronics. The realization of DW p-n junction in LN on an insulator (LNOI) is expected to push forward the development of opto-electronics integrated chips based on LN. This paper provides a concise review on the study of DWs in LN, including the fabrication techniques, the conduction mechanism and types of DWs as well as the development of applications based on DWs, especially the achievement of DW p-n junction. Furthermore, combined with the hot potential applications, the key issues, challenges and opportunities in the development DW-based opto-electronic devices based on LN were summarized.