Experiments showed that the non-equiliubrium optical response of epitaxial YBa2Cu3O7-δ films below Tc existed with the illumination of He-Ne laser (λ=0.63μm). We have also found that near the transition region, where dR/dT is vanishing, the optical response becomes a strong nonlinear functions of current. A model was presented to explain the mechanism of the nonlinear behavior based on the interactions between photoexcited quasiparticles and the vortex in high Tc superconductor. We believe that the mechanism of the dissipation induced by light illumination in transition region may be correlated with the mechanism of “irreversibility line” or that of “broaden resistive transition” in magnetic fields.