The invention relates to a preparation method of a thermoelectric refrigerator for high orbit space; the preparation method comprises the following steps of: preparing a thermoelectric material sheet, a thermoelectric element, a metallization pattern and a flow deflector, integrally welding, grinding, carrying out ultrasonic cleaning, welding outgoing lines, and carrying out temperature and mechanics aging test of 'electrical aging and temperature cycle as well as variable frequency vibration'; the preparation method is characterized in that two layers of nickel are respectively plated on two end surfaces of the thermoelectric material sheet; a layer of nickel is plated on the metallization pattern; and a layer of nickel and a layer of tin are plated on exposed parts of the flow deflector through barrel plating. Through nickel plating of the thermoelectric material sheet and the metallization graph and nickel plating and tin plating of the flow deflector together with material optimization, welding, grinding, ultrasonic cleaning and screening of destructive tests, the thermoelectric refrigerator prepared by the method has the advantages that the space radiation resistant capacity reaches 300 Krad (Si), the failure rate reaches 200fit, the temperature difference is large, the refrigeration power is high, has the characteristics of strong impact resistance and vibration mechanical property, high reliability, small volume and the like and is particularly suitable for being applied to the high orbit space.