Abstract: Nano silver paste for low temperature sintering bonding was studied. The optimal ratio of nano silver particles to micro silver particles in the silver paste was calculated and then was made into composite silver paste. The effect of different solvents on the porosity of the sintering joint was investigated. Meanwhile, the hardness, elastic modulus, and plasticity of the sintered joints by nano silver paste and micro silver paste were studied. The results indicated that the composite silver paste using the mixed organic solvent improved the quality of the sintered joints under 250°C. The porosity in the joints was significantly lower using the mixed organic solvent than that using glycol. Compared with nano silver sintered joints, the sintered joints using composite silver paste showed larger indentation area but lower hardness and elastic modulus. When the sintering time ranged from 10min to 30min, the plasticity of the composite silver joints was higher than that of the nano silver sintered joints.