The oxygen evolution reaction (OER) is the main obstacle to overall water splitting and therefore the focus of recent research. Perovskite oxides have been regarded as promising OER catalysts due to their superior activity and compositional flexibility. In this work, a nanofilm of BaSrCoFeO deposited on nickel foam (BSCF-NF) was fabricated by pulsed laser deposition (PLD), and the real-time dynamic surface change was observed by in situ Raman spectroscopy. In addition, a surface reductive strategy is applied to BSCF-NF, which is then demonstrated to facilitate the formation of active species on B-site cations, resulting in enhanced OER activity. The reconstruction activation potential of BSCF-NF is reduced after the reductive treatment. The correlation between surface electron structure and catalytic activity is established and discussed. This work provides not only a facile strategy for promoting the formation of active species but also an in-depth understanding of the fundamental processes of surface reconstruction and the origins behind the improved OER performance for perovskite catalysts.