Time-series photometric observations were made for the High Amplitude \delta Scuti star CW Ser between 2011 and 2012 at the Xinglong Station of National Astronomical Observatories of China .
After the frequency analysis of the light curves , we confirmed the fundamental frequency of f = 5.28677 cd ^ { -1 } , together with 8 harmonics of the fundamental frequency , 7 of which are newly detected .
No additional frequencies were detected .
The O - C diagram , produced with the 21 newly determined times of maximum light combined with those provided in the literature , helps to obtain a new ephemeris formula of the times of maximum light with the pulsation period of 0.189150355 \pm 0.000000003 days .