  Based on the framework of the Isospin-Dependent Quantum Molecular Dynamics
(IQMD) model in which the initial neutron and proton densities are sampled
according to the droplet model, the correlation between triton-to-$^{3}$He
yield ratio (R(t/$^{3}$He)$=$Yield(t)/Yield($^{3}$He)) and neutron skin
thickness (${\delta}_{np}$) in neutron-rich projectile induced reactions is
investigated. By changing the diffuseness parameter of neutron density
distribution in the droplet model for the projectile to obtain different
${\delta}_{np}$, the relationship between ${\delta}_{np}$ and the corresponding
R(t/$^{3}$He) in semi-peripheral collisions is obtained. The calculated results
show that R(t/$^{3}$He) has a strong linear correlation with ${\delta}_{np}$
for neutron-rich $^{50}$Ca and $^{68}$Ni nuclei. It is suggested that
R(t/$^{3}$He) could be regarded as a good experimental observable to extract
${\delta}_{np}$ for neutron-rich nuclei because the yields of charged particles
triton and $^{3}$He can be measured quite precisely.
