Shape stabilized binary paraffin/desulfurization gypsum composites with different volume fractions were prepared by melt mixing， vacuum negative pressure adsorption and direct incorporation methods. The mechanical properties and thermal performance of the composites were determined. The results show that the phase transition temperature of binary paraffin is 54.8 ℃ and the latent heat of phase transition is 96.32 J/g when the mass ratio of solid paraffin to liquid paraffin is 1.0∶1.0. The shape stabilized binary paraffin had good thermal stability and dispersion when the mass ratio of binary paraffin/expanded perlite is 2.5∶1.0. The mechanical properties and thermal conductivity of the composites decrease with the increase of the content of shape stabilized binary paraffin. The thermal inertia of the composites with 30%（by volume）shape stabilized binary paraffin is obviously improved.