  It is crucially important to find an observable which is independent on the
acceptance and late collision process, in order to search for the possible
Critical Point predicted by QCD. By utilizing A Multi-Phase Transport (AMPT)
model and Ultra Relativistic Quantum Molecular Dynamics (UrQMD) model, we study
the centrality and evolution time dependence of higher moments of net-baryon
distribution in Au + Au collisions at $\sqrt{s_{NN}}=17.3$ GeV. The results
suggest that Kurtosis and Skewness are less sensitive to the acceptance effect
and late collision process. Thus, they should be good observables providing the
information of the early stage of heavy ion collision. In addition, our study
shows that the Kurtosis times $\sigma^{2}$ of net-proton distribution are quite
different to that of net-baryon when collisions energy is lower than
$\sqrt{s_{NN}}$ = 20 GeV, the Monte Calor calculations on
Kurtosis$\cdot\sigma^{2}$ have a deviation from the theoretical predictions.
