The invention discloses a thermocouple fixation device for a test, and an installation method. The thermocouple fixation device comprises a fixation part and an insulation part, wherein the fixation part comprises a semicircular-shaped base and a semicircular-shaped cutting sleeve, the cutting sleeve and the base are arranged respectively at an upper position and a lower position, the two form a hole for a thermocouple temperature sleeve to pass through, one end of the cutting sleeve is connected with the base through a shaft, and the cutting sleeve and the base can rotate along the shaft; the other end of the cutting sleeve cooperates with the base through a buckle so as to realize fixation of a thermocouple; and the insulation part sleeves the thermocouple to seal a gap between the thermocouple and the temperature sleeve.