  The observation of GW150914 indicated a new independent measurement of the
luminosity distance of a gravitational wave event. In this paper, we constrain
the anisotropy of the Universe by using gravitational wave events. We simulate
hundreds of events of binary neutron star merging that may be observed by
Einstein Telescope. Full simulation for producing process of gravitational wave
data is employed. We find that 200 of binary neutron star merging in redshift
$(0,1)$ observed by Einstein Telescope may constrain the anisotropy with an
accuracy comparable to the result from Union2.1 supernovae. This result shows
that gravitational waves can be a powerful tool in investigating the
cosmological anisotropy.
