  In this work, we perform the electroweak phase transition study with the
Georgi-Machacek model. We investigate both the one-step and two-step strong
first order electroweak phase transition (SFOEWPT). The SFOEWPT viable
parameter spaces could be tested by the future 14 TeV LHC, HL-LHC, and ILC. The
LHC Higgs signal strength measurements severely bound the SFOEWPT valid
parameter spaces, a tinny region of the mixing angle between the neutral fields
of the isospin-doublet and isospin-triplet scalars around $\alpha\sim 0$ can
allow the two-step SFOEWPT to occur. The triplet vacuum expectation value (VEV)
is crucial for both SFOEWPT and related Higgs phenomenology. The two-step
SFOEWPT can be distinguished from the one-step SFOEWPT through the triple Higgs
coupling searches and the low mass doubly charged Higgs searches at colliders.
