  The jet composition of GRB plays an important role in understanding the
energy dissipation and radiation mechanisms in GRB physics, but it is poorly
constrained from the observational data. Recently, an interesting long-duration
GRB 230307A with redshift $z=$0.065 has attracted great attention. The lack of
detected thermal emission and mini-structure of prompt emission lightcurve of
this burst suggest that the outflow is Poynting-flux-dominated and point
towards the ICMART model. In this paper, we invoke two independent methods to
investigate the jet composition of GRB 230307A. The high magnetization
parameter ($\sigma>7$ or ever large) for$R_0=10^{10}$ cm that is used to
suppress thermal component, strongly suggests that a significant fraction of
the outflow energy is likely in a Poynting flux entrained with the baryonic
matter. Moreover, it is found that the radiation efficiency of this burst for
typical values $\epsilon_e=0.1$ and $\epsilon_B=0.01$ can reach as high as
$~50\%$ which disfavors the internal shock model, but is consistent with ICMART
model. Finally, a possible unified picture to produce GRB 230307A originated
from a compact star merger is also discussed.
