The oscillation behaviors in T-jets reactors with excitation are experimentally studied by a flow visualization technique. The images of the smoke-seeded flow are captured by a particle imaging velocimetry (PIV) system and a high-speed camera. The effects of the Reynolds number, the excitation frequency and the excitation amplitude on the oscillation behaviors in T-jets reactors have been investigated. The impingement plane flaps periodically caused by the pulsed inflow, and the excited flapping frequencies of the impingement planes are equal to the excitation frequencies. Different oscillation behaviors in T-jets reactors with excitation are identified, and the interaction between the self-sustained oscillations and the excited flapping oscillations is investigated and discussed. Results show that the excitation as well as the geometry parameters of T-jets reactors has significant effects on oscillation behaviors. The excited oscillation amplitudes of impingement planes increase with Reynolds numbers and excitation amplitudes, but non-monotonically decrease with excitation frequencies. (C) 2015 Elsevier Ltd. All rights reserved.