  With the calculated guiding center radius $R_{guiding}$ and birth radius
$R_{birth}$, we investigate the role of radial migration on the description of
lithium evolution in the Galactic disk based on the upper envelope of the A(Li)
vs. [Fe/H] diagram. Using migration distances, we find that stars in the solar
neighborhood are born at different locations in the galactic disk, and cannot
all be explained by models of chemical evolution in the solar neighborhood. It
is found that the upper envelope of the A(Li) vs. [Fe/H] diagram varies
significantly with $R_{birth}$, which explains the decrease of Li for
super-metal-rich (SMR) stars because they are non-young stars born in the inner
disk. The upper envelope of Li-$R_{birth}$ plane fits very well with chemical
evolution models by Grisoni et al. for $R_{birth} = 7 - 12$ kpc, outside which
young stars generally lack sufficient time to migrate to the solar
neighborhood. For stars born in the solar neighborhood, the young open clusters
and the upper envelope of field stars with age $<$ 3 Gyr fit well with
theoretical prediction. We find that calculations using stars with ages less
than 3 Gyr are necessary to obtain an undepleted Li upper envelope, and that
stars with solar age (around 4.5 Gyr) have depleted around 0.3 dex from the
original value based on the chemical evolution model of Grisoni et al.
