Abstract: The refractive index of liquid is related to the density of liquid, the density of liquid is related to thetemperature of liquid based on a general refractive index equation of transparent material. It is easy for measuring the temperature dependence of the refractive index of liquid by using optical interference. The thermal expansion coefficient of liquid is obtained and the formulas of refractive index of liquid is discussed.

Key words: liquid, refractive index, temperature, expansion coefficient