The transparent Y3Al5O12(YAG) ceramics were fabricated by hotpressing sintering(HP) with LiF as sintering aid in this work.The optical properties and microstructure of YAG transparent ceramics were characterized, and the effects of LiF on the properties of hotpressing sintered YAG ceramics were further analyzed by electrochemical impedance spectroscopy.The results show that LiF as sintering aid was beneficial to promote the grain growth of YAG ceramic and helped to increase the density of YAG ceramics. The impedance spectroscopy analysis showed that the grain boundary resistance of YAG ceramics with more LiF added is higher,which indicated that LiF contributed to the elimination of impurities such as “carbon contamination” at the grain boundary. When w(LiF)=1.0%,the YAG transparent ceramics with good properties can be prepared by vacuum hot pressing at 1 450 ℃ and 50 MPa for 1 h.The inline transmittance of the sample was 58% at the wavelength of 400 nm, 68% at the wavelength of 1 100 nm, and 75% at the wavelength of 2 500 nm.