The invention discloses a method for blocking a thermocouple pipe conduit. The method comprises the steps of S1, cutting off the thermocouple pile conduit from a sealing seat, wherein a mounting partof the conduit is remained in an inserting hole of the sealing seat; S2, performing tube drilling on the upper end of the inserting hole so as to remove the upper end part of the mounting part; S3, processing a blocking part on the inner wall of the upper end of the inserting hole, wherein the blocking part comprises a first blocking section and a second blocking section which intercommunicate; the first blocking section is positioned at an opening of the inserting hole; a third blocking section which communicates with the second blocking section is formed in an inner channel of the mounting part; S4, arranging plugs which fit the second blocking section and the third blocking section into the second blocking section and the third blocking section; and S5, welding the first blocking section to form a welded joint in the first blocking section; and sealing the plug into the inserting hole by welding. With the adoption of the method, the leakage of the thermocouple pipe conduit is handled; the completeness of the pressure boundary of a loop is ensured; the huge loss on cost and construction period caused by overall replacing or partial replacing of the thermocouple pipe conduit is avoided.