In order to describe optical clearing effects of glycerol quantitatively, tissue-simulating phantoms whose optical properties are identical with that of human skin tissue are introduced. The optical clearing effects of tissue-simulating phantoms with different concentrations of glycerol have been studied by using double integrating spheres system and Fourier transform-infrared (FT-IR) spectrophotometer. The results show that the scattering coefficients of skin phantoms decrease with the rising glycerol concentration at the wavelength of 632.8 nm, and the light penetration depth increases and the maximum percentage attains to 48.76%. Meanwhile, with the increase of glycerol concentration, the transmittance of skin phantoms increases as well, which equales the reduction of total attenuation coefficients. Therefore, the correlation can be obtained quantitatively between the optical clearing effects induced by glycerol and its concentration in tissue-simulating phantoms.