The invention belongs to the technical field of rubber, and particularly relates to odorless EPDM mixed synthetic rubber and a preparation method thereof. According to the main technical scheme, the odorless EPDM mixed synthetic rubber comprises the following components in parts by weight: 100 parts of ethylene propylene rubber, 30-45 parts of a reinforcing agent, 1-2 parts of a vulcanizing agent,3-6 parts of an accelerant, 5-10 parts of an active agent, 2-4 parts of a neutralizer, 1-2 parts of a coupling agent, 75-95 parts of a filler and 80-110 parts of a plasticizer, wherein the ethylene propylene rubber is ethylene propylene diene monomer, the third monomer of the ethylene propylene rubber is 5-ethylidene bicyclo [2.2. 1] hept-2-ene, and the content of the third monomer does not exceed 5%; the reinforcing agent is white carbon black; the plasticizer is paraffin oil; the vulcanizing agent is sulfur; the accelerant is at least one of thiazoles, sulfenamides and thiocarbamates; the coupling agent is gamma-(2, 3-epoxypropoxy) propyltrimethoxysilane. The odorless EPDM mixed synthetic rubber and the preparation method thereof have the characteristics of odorless volatilization of materials, health and cleanness, low exhaust emission in the production process and good environmental protection benefit.