  The Planck constant $h$ is one of the most significant constants in quantum
physics. Recently, the precision measurement of the numeral value of $h$ has
been a hot issue due to its important role in establishment for both a new SI
and a revised fundamental physical constant system. Up to date, two approaches,
the watt balance and counting atoms, have been employed to determine the Planck
constant at a level of several parts in $10^8$. In this paper, the principle
and progress on precision measurement of the Planck constant using watt balance
and counting atoms at national metrology institutes are reviewed. Further
improvements for the Planck constant determination and possible developments of
a revised physical constant system in future are discussed.
