The invention discloses a tunnel karst treatment method by adopting high-pressure jet grouting piles to replace drilling grouting, and belongs to the field of underground engineering construction. Fora karst cave with known position and boundary, with one end boundary of the karst cave in the direction of a tunnel as an initial pile forming surface, a row of high-pressure jet grouting piles engaged in sequence is driven; after the construction of the row of high-pressure jet grouting piles is finished, a next row of high-pressure jet grouting piles is constructed in the direction of the tunnel until the final row of high-pressure jet grouting piles on the other end boundary of the karst cave is constructed; two adjacent rows of high-pressure jet grouting piles are kept in engagement; andeach row of high-pressure jet grouting piles covers a karst cave body on the section thereof. The method can use engaged pile bodies for total filling in a certain areas; and the formed pile bodies can be long or short according to the boundaries of the detected karst cave, so that the method is safer and more reliable under the condition of using cement paste.