Considering a moving two-level atom coupling with a single-mode thermal light field through intensity-dependence, reduced entropy change and entropy exchange between the atom and the field is studied by using quantum reduced entropy, entanglement is measured by using concurrence, the effect of initial atomic state, the mean photon number of thermal field and the field-mode structural parameter on entropy exchange and entanglement are investigated. The results show that reduced entropy change and entanglement exhibit periodic evolution. When initial parameters are suitable, the complete exchange between the atomic and field reduced entropy occurs, which means there is a form of anti-correlated behavior between field and atom. In addition, the increase of field-mode structural parameter weakens reduced entropy exchange, and shortens period of entropy exchange. Entanglement between atom and field decreases as the transition photon number increases.