A series of MS sealants were prepared based on different grades of organosilicon-modified polyether (MS) prepolymer as base polymer. The effects of the MS prepolymer and the amount of carbon black on the tensile strength and shear strength of the MS sealant were investigated. Then the weatherability and bonding properties of the prepared MS sealants with different types of aluminum substrates were studied. The experimental results indicated that the molecular structure of MS prepolymer had a great influence on the strength and elasticity of MS sealant. High-modulus MS sealant could be obtained by compounding heavy calcium carbonate, nano-calcium carbonate, with 7% carbon black as a filler. Furthermore, the adhesive properties and weather resistance of the resulting sealant were excellent.