We explore the properties of dark energy from recent observational data, including the Gold Sne Ia, the baryonic acoustic oscillation peak from SDSS, the CMB shift parameter from WMAP3, the X-ray gas mass fraction in cluster and the Hubble parameter versus redshift. The $Lambda CDM$ model with curvature and two parameterized dark energy models are studied. For the $Lambda CDM$ model, we find that the flat universe is consistent with observations at the $1sigma$ confidence level and a closed universe is slightly favored by these data. For two parameterized dark energy models, with the prior given on the present matter density, $Omega_{m0}$, with $Omega_{m0}=0.24$, $Omega_{m0}=0.28$ and $Omega_{m0}=0.32$, our result seems to suggest that the trend of $Omega_{m0}$ dependence for an evolving dark energy from a combination of the observational data sets is model-dependent.
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