  We study the effect of in-medium mass-shift on transverse-momentum spectrum
and elliptic anisotropy of $\phi$ meson. It is found that the mass-shift
enhances the $\phi$ yields and suppresses the elliptic flow $v_2$ in large
momentum region, and the effects increase with the increasing mass-shift. The
effects are various for different sources and decrease with the increasing
expanding velocity. We further study the effects for parts of all $\phi$ meson
with mass-shift, and the effects decrease with the decreasing probability of
$\phi$ meson with mass-shift. Since the different mass-shift lead to different
transverse-momentum spectrum and $v_2$, our study may provide a way to restrict
the ranges of in-medium mass-shift of $\phi$ meson in high-energy heavy-ion
collisions.

Nuclear Theory