The semiconductor industry is the backbone of the high-tech and information age. Lithography technology, one of the core technology of the semiconductor industry, has become a key research subject all around the world. This article mainly discusses the light source of 13.5 nm Extreme Ultraviolet Lithography (EUVL) by using Laser-Produced Plasma (LPP). It makes a brief introduction to the principles behind this technology and the development history of this field at home and abroad. The introductions include the materials used in the multilayer mirror, and rationale for the selection of materials, the shape and design of the target and the type of laser. At the same time, this article points out that the main problems for the EUVL are light debris reduction and the conversion efficiency improvement of EUV light．This paper also gives special analysis of the light source output devices of 13.5 nm EUVL machines produced by international famous companies--Gigaphoton of Japan and ASML of the Netherlands, which can generate more than 100 W level EUV power. Finally, this article summarizes and forecasts future research related to this technology.