Abstract: The main achievements of lake optics in recent several decades are simply presented,which include optical properties of lake water,the observation,transmission and calculation of underwater radiation.Research emphasis of lake optics are thoroughly expounded,including determination of absorption coefficient S of yellow substance,influence of UV-Bradiation on lake ecosystem,ecological effect of light,photochemical processes,calculation of lake primary production by the bio-optical model and analysis of restrictive factors for eutrophication and protection of lake eutrophication1.At last,the main applications of lake optics,such as calculation of lake primary production and Chl-a,demarcation of detection of suspended matter and water color remote sensing,are summarized.Moreover,the paper also points out research orientations,the gap between the level of lake optics reasearch in China and the worldcs advanced levels and researches required in China.