Controllable and scalable preparation of electrocatalyst materials holds significant importance for their practical application. Magnetron sputtering is a highly effective synthesis method, known for its producing uniform films and allowing easy control of component compositions. In this paper, we propose an in-situ synthesis method for layered double hydroxide (LDH) electrocatalysts through sacrificing magnetron sputtered films. The resulting FeCo-LDH catalyst demonstrated a low overpotential of only 300 mV at 10 mA·cm⁻². Furthermore, we conducted spectroscopic analysis to investigate the surface changes of the catalysts during the oxygen evolution reaction (OER) process. Our findings indicated that the formation of Co oxyhydroxides plays a beneficial role in enhancing the catalytical performance of the FeCo-LDH for OER reaction. This restructuring strategy of converting a magnetron-sputtered sacrificial film into a catalytical LDH introduces a new avenue to the synthesis of transition metal-based electrocatalysts.