  We report on the first dark-matter (DM) search results from PandaX-I, a low
threshold dual-phase xenon experiment operating at the China Jinping
Underground Laboratory. In the 37-kg liquid xenon target with 17.4 live-days of
exposure, no DM particle candidate event was found. This result sets a
stringent limit for low-mass DM particles and disfavors the interpretation of
previously-reported positive experimental results. The minimum upper limit,
$3.7\times10^{-44}$\,cm$^2$, for the spin-independent isoscalar
DM-particle-nucleon scattering cross section is obtained at a DM-particle mass
of 49\,GeV/c$^2$ at 90\% confidence level.
