  We review recent studies about anisotropic flows ($v_1, v_2, v_3$) of
charmonium in the quark-gluon plasma produced in relativistic heavy-ion
collisions. Collective flows of the bulk medium are developed due to the
anisotropic pressure gradient of the medium. Strongly coupled with the bulk
medium, charm quarks carry collective flows from the expanding medium, which
will be inherited by the regenerated charmonium via the coalescence process. In
event-by-event collisions where nucleon positions fluctuate from the smooth
distribution, there is triangularity in the medium initial energy density.
Triangular flows of the bulk medium and heavy flavor particles can be developed
due to the initial fluctuations. In the longitudinal direction, the
rapidity-odd distribution of the initial energy density is induced by the
rotation of the medium in non-central heavy-ion collisions. Charmonium suffers
biased dissociation along positive and negative $x$-directions in forward
(backward) rapidity. The directed flow of charmonium becomes non-zero. The
directed, elliptic and triangular flows ($v_1, v_2, v_3$) of charmonium come
from the anisotropic initial distributions of the medium energy density in the
transverse and longitudinal directions.
