We report the discovery of a Tidal Disruption Event (TDE) candidate occurring in the Active Galactic Nucleus SDSS J02277-0420. A sudden increase in flux of J0227-0420 during the second half of 2009 is clearly shown in the long-term optical, UV, and NIR light curves. A plateau phase, following an initial decline, is seen in the NUV and optical u, g, r, i light curves. The plateau phase in the NUV band lags behind the optical ones by approximately 70–80 days with also a much shorter duration, i.e. ∼7–15 days against ∼40–50 days. The long-term NUV/optical (after the plateau phase), NIR and MIR light curves can be well characterized with a form of L(t) ∝ t−β, consistent with the expectation of a TDE. The lag between the NUV and optical plateau phase may attribute to the viscosity decay, i.e. the fallback material moving towards the BH after the stellar streams colliding with the pre-existing accretion disk, implying that the optical/NUV flares are originated from the accretion process. The index β of the NIR band (∼ 2.1 − 2.7) is steeper than that of the UV/optical (∼ 0.7 − 1.0) and MIR bands (∼ 1.2 − 1.4), suggesting that a certain fraction of the dust in the inner region of the dusty torus may be sublimated during the TDE phase. Our results indicate that, due to collisions between stellar debris and pre-existing disk, the light curves of TDEs occurring in AGN may show distinctive features, which may shed new light on the accretion process.