Yb: CaF2-SrF2 crystals are grown by Bridgman technique. The spectroscopic properties, thermal diffusion coefficients and thermal expansion coefficients at different temperatures are studied. Thermal conductivity at 300 K and thermal expansion coefficient are calculated. The absorption spectra, fluorescence spectra, thermal properties of crystals are analyzed by comparison method. The results show that the absorption and emission cross sections are larger in the high concentration SrF2 disordered crystal. And also the emission cross section is large and wide at 1040 nm in the Yb: CaF2-SrF2 (19%) crystal. It demonstrates that for different ratios of CaF2 and SrF2 in the disordered crystals, the spectroscopic properties are different. The main possible reason is the different disorders, low symmetry, low symmetry optical centers in the disordered crystal. It can also be seen that the disordered crystal has a good thermal conductivity.