The invention relates to a thread-mounted high-voltage fusion tube. Compared with the prior art, the thread-mounted high-voltage fusion tube has the advantage that the defect that a fusion core is inconvenient to replace in the structural design of the fusion tube is avoided. The thread-mounted high-voltage fusion tube comprises a fusion tube sleeve, wherein an upper tube cap is arranged at the upper end of the fusion tube sleeve; a lower tube cap is arranged at the lower end of the fusion tube sleeve; the upper tube cap is of an inner thread structure; the upper end of the fusion tube sleeve is of an outer thread structure; a boss is arranged at the upper part of the upper tube cap; a line nose connection block is arranged on the boss; a through hole is formed in the side part of the upper tube cap; a notch is formed in the side part of the upper end of the fusion tube sleeve; the through hole is of an inner thread structure; the upper tube cap is arranged at the upper end of the fusion tube sleeve via a thread and the through hole corresponds to the position of the notch after the upper tube cap and the fusion tube sleeve are installed in place; and a threaded pin is arranged in the through hole through the thread and abuts on the notch. The mounting mode of the fusion tube is simplified.