The invention relates to a foamed rubber sealing material and a manufacturing method thereof. The foamed rubber sealing material is composed of 100 parts of main material, 6-8 parts of reinforcing colorant, 20-40 parts of plasticizer, 1-2 parts of dispersing agent, 8-12 parts of foaming agent, 8-10 parts of vulcanizing agent, 1-2 parts of stearic acid, 1-2 parts of accelerator, 3-6 parts of protective agent and 60-80 parts of filler. The main material CR:EPDM:NR ratio is 70:(10-20):(10-20), the plasticizer brown ointment:naphthenic oil ratio is 1:3, the accelerator DETU:TMTM ratio is 1:1, and the protective wax:anti-aging agent 445:anti-aging agent ODA ratio is 1:1:1. The manufacturing method comprises the following steps: rubber mixing, powder mixing, discharging, primary vulcanizing and foaming, secondary vulcanizing and foaming, and normal-temperature natural cooling for 10-15 days. The foamed rubber sealing material has the advantages of low density, high toughness, low thermal conductivity, water resistance, favorable aging resistance, excellent elasticity, excellent shock-absorbing capacity, excellent flame retardancy, environmental protection and no toxicity.