Boron's unique electron deficiency allows for the formation of various borophene polymorphs that have the potential for superconductivity. Herein, we have introduced a new route to realize high superconductivity in borophene through kagome and honeycomb boron layers assembly. We have designed a tri-layer borophene, named hP8-B, consisting of two AA-stacked kagome layers with a honeycomb layer serving as the interlayer. hP8-B possesses high superconductivity with an estimated Tc of 35.6 K, holding the highest value in any elemental 2D materials. The high Tc is mainly contributed by the strong coupling of σ-bonding electrons of the kagome layers and in-plane vibrational modes, which differs from that in other superconductive borophene polymorphs. Electronic band structure calculations showcase the existence of a Dirac cone near the Fermi level, indicating that hP8-B may be a potential topological superconductor. The superconductivity of hP8-B can be enhanced to 46.4 K under a biaxial tensile strain of 3% and doping density of 0.0375 holes per atom, due to the softening of the in-plane vibrational modes.