  The striking resemblance of high multiplicity proton-proton (pp) collisions
at the LHC to heavy ion collisions challenges our conventional wisdom on the
formation of the Quark-Gluon Plasma (QGP). A consistent explanation of the
collectivity phenomena in pp will help us to understand the mechanism that
leads to the QGP-like signals in small systems. In this study, we introduce a
transport model approach connecting the initial conditions provided by PYTHIA8
with subsequent AMPT rescatterings to study the collective behavior in high
energy pp collisions. The multiplicity dependence of light hadron productions
from this model is in reasonable agreement with the pp $\sqrt{s}=13$ TeV
experimental data. It is found in the comparisons that both the partonic and
hadronic final state interactions are important for the generation of the
radial flow feature of the pp transverse momentum spectra. The study also shows
that the long range two particle azimuthal correlation in high multiplicity pp
events is sensitive to the proton sub-nucleon spatial fluctuations.
