  A preliminary estimation of gravitational waves (GWs) from the
extreme-mass-ratio-inspirals (EMRIs) system in the Galactic Centre (GC) is
given for the 37 observed S-stars revolving around the supermassive black hole
(SMBH) at Sagittarius (Sgr) A*. Within this century, the total strain of the
gravitational waveform calculated from the post-Newtonian (PN) method with
eccentricity is well below the current planned sensitivity of
pulsar-timing-array (PTA). New technology might be required in order to extract
GW signal from this EMRIs system for future PTA detections.
