We present new photometry of the eclipsing binary ZZ Cyg. From all accumulated eclipsing times, we constructed the (O–C) curve, which can be described by a downward parabola with a possible light-time orbit. The period decrease rate is dP/dt=-5.73(±0.18)dyr-1. The modulated period, semi-amplitude and eccentricity for the light-time orbit are Pmod=71.4(±1.1)yr, A=0.0071(±0.0005)day and e=0.420(±0.053), respectively. After removing effects of the magnetic activity, this kind of cyclic oscillation may be attributed to light-time effect via an additional companion. By using the W-D code, the photometric model was updated, which identified that ZZ Cyg is a near-contact binary. We find that a hot spot may occur on the primary that explains the asymmetric light curve. The secular period decrease may possibly cause the fill-out factor of the primary to increase. Finally it will finally fill its Roche lobe. This kind of binary, ZZ Cyg, may evolve into contact binary star.