The invention discloses heat curing silicone rubber crosslinked with a polyamine compound and a preparation method thereof. The preparation method comprises the following steps of: cohydrolyzing dimethyldiethoxysilane and chloropropyl-methyl-2-silane to obtain chloropropyl-7-central-4-methyl siloxane; cohydrolyzing the chloropropyl-7-central-4-methyl siloxane and 8-central-4-methyl siloxane to obtain chloropropyl methyl polysiloxane; using the chloropropyl methyl polysiloxane as a based adhesive, polyamines as a coupler, a gas-phase-method white carbon black as a reinforcing material and zincoxide as an acid absorbent; and preparing by heat curing. The heat curing silicone rubber of the invention not only has excellent mechanical properties, but also overcomes some defects of a traditional curing system and has favorable economic benefits and popularization application values.