  It is generally believed that conductivity platform can only exist in
insulator with topological nontrivial bulk occupied states. Such rule exhibits
in two dimensional quantum (anomalous) Hall effect, quantum spin Hall effect,
and three dimensional topological insulator. In this letter, we propose a spin
Hall conductivity (SHC) platform in a kind of three dimensional metallic
materials with triply degenerate points around the Fermi level. With the help
of a four bands \textbf{k}${\cdot}$\textbf{p} model, we prove that SHC platform
can form between $|\frac{3}{2},\pm\frac{3}{2}\rangle$ and
$|\frac{1}{2},\pm\frac{1}{2}\rangle$ states of metallic system. Our further ab
initio calculations predict that a nearly ideal SHC platform exhibits in an
experimentally synthesized TaN. The width of the SHC platform reaches up to
0.56 eV, hoping to work under high temperature. The electrical conductivity
tensor of TaN indicates that its spin Hall angle reaches -0.62, which is larger
than many previous reported materials and make it an excellent candidate for
producing stable spin current.
