The diffusion light detected from bio-tissue surface contains tissue optical parameters information. So tissue optical parameters can be obtained indirectly by the diffusion light measuring, then optical parameters resolved tissue structure, physiology and pathology state information can be obtained finally. A multi-distance measurements method is employed in this paper. A single parameter (reduced scattering coefficient) fitting method and a double parameters (reduced scattering coefficient and amplitude factor) fitting method on the basis of the least square Newton fitting algorithm is used to derive the optical parameters respectively. For the finite-thickness homogenous tissue, it can be concluded that the rest terms in expressions of diffusion reflectance and transmittance for the corresponding tissue geometries that subtract the exponential term contained source-detector distance depend on the detected position weakly. And some discussions are included. Additionally, the probable structure information for the finite-thickness two-layered slab tissue can be obtained from the diffusion reflectance and transmittance measurements according to the discrepancies of fitting reduced scattering coefficient and the sign (positive or negative) of the amplitude factor.