  Classical scale invariance (CSI) may shed light on the weak scale origin, but
the realistic CSI extension to the standard model requires a bosonic trigger.
We propose a scalar Dark Matter(DM) field $X$ as the trigger, establishing a
strong connection between the successful radiative breaking of CSI and DM
phenomenologies. The latter forces the breaking scale to $\sim {\cal O}(\rm
TeV)$. It brightens the test prospect of this scenario via gravitational wave,
a sharp prediction of CSI phase transition (CSIPT), which is first order and
has strong supercooling. Moreover, we carefully deal with some techniques which
are commonly used to analyze CSIPT but maybe missed. In particular, we clarify
the imprecision of Witten's formula used in the single field case to calculate
the bubble nucleation rate and stress that the essence of Witten's
approximation is the validity of high temperature expansion.
