Changes of the Period and the Light Curves of the Contact Binary V1073 Cygni

Observational evidence of unstable behavior for the WUMa-type binary system V1073 Cygni is presented in this paper.Around 1939 the period of the binary suddenly decreased by 0.580 seconds and again suddenly decreased by 0.746 seconds around 1981.Obvious variable O'Connell effect of the light curves in V can be seen.The relation between the changes in the orbital period and variation in the O'Connell effect and possible reasons for the unstable behavior of V1073 Cyg were discussed.