  We propose a mechanism to pin skyrmions in chiral magnets by introducing
local maximum of magnetic exchange strength, which can be realized in chiral
magnetic thin films by engineering the local density of itinerate electrons.
Thus we find a way to artificially control the position of a single skyrmion in
chiral magnetic thin films. The stationary properties and the dynamical pinning
and depinning processes of an isolated skyrmion around a pinning center are
studied. We do a series of simulations to show that the critical current to
depin a skyrmion has linearly dependence on the pinning strength. We also
estimate the critical current to have order of magnitude
10^{7}\sim10^{8}A/m^{2} .
