Multi-layer insulation board for outer wall of building

The utility model discloses a building outer wall multi-layer insulation board, and particularly relates to the technical field of insulation boards, the building outer wall multi-layer insulation board comprises a first insulation board and a second insulation board, when the first insulation board and the second insulation board need to be spliced, an insertion block is inserted into a groove, a triangular block continues to move towards the first insulation board, and when a trapezoidal rod encounters an insertion groove in the top of the triangular block, the triangular block moves towards the second insulation board. The trapezoidal rods are reset under the influence of the elastic force of the spring telescopic rods and are inserted into the inserting grooves again, the second heat preservation plate is fixed, then the first heat preservation plate and the second heat preservation plate are spliced, and after the first heat preservation plate and the second heat preservation plate are spliced, a first t