  We report the creation of ultracold ground state
$^{6}\textrm{Li}^{40}\textrm{K}$ polar molecules with high efficiency. Starting
from weakly-bound molecules state, stimulated Raman adiabatic passage (STIRAP)
is adopted to coherently transfer the molecules to their singlet ro-vibrational
ground state $|\textrm{X}^{1}\Sigma^{+},v=0,J=0>$. By employing a singlet
STIRAP pathway and low-phase-noise narrow-linewidth lasers, we observed a
one-way transfer efficiency of 96(4)\,\%. Held in an optical dipole trap, the
lifetime of the ground-state molecules is measured to be 5.0(3)\,ms. The large
permanent dipole moment of LiK is confirmed by applying a DC electric field on
the molecules and performing Stark shift spectroscopy of the ground state. With
recent advances in the quantum control of collisions, our work paves the way
for exploring quantum many-body physics with strongly-interacting
$^{6}\textrm{Li}^{40}\textrm{K}$ molecules.
