From a large volume of literature we have collected a total of 16818 datapoints of effective observation of BL Lac object S5 0716+714 in the optical band, and constructed its long-term light curve from 1994 to 2006 AD. The light curve shows that S5 0716+714 is very active and exhibits very complicated non-sinusoidal variations. We used power spectrum method to analyze the period of light curve variation. Our results show that the long-term period of variation is 1.1 year. Time of coincidence is possible, Raiteri et al. have found the period of 3.3 year, which may be a multiple of 1.1-year periods. We expect next burst in 2006 July.