The lack of highly reproducible manufacturing technology hinders the development and commercial application of perovskite light‐emitting diodes (PLEDs). In order to solve this problem, the in‐situ fluorescence monitoring technology is proposed to obtain efficient and reproducible PLEDs. By dynamic monitoring the photoluminescence of the perovskite film in the spin‐coating process to precisely control the anti‐solvent dropping time, high‐quality and reproducible perovskite films with high photoluminescence quantum yield (PLQY), high crystallinity and low trap density can be obtained. As a result, the fabricated green and blue PLEDs show high external quantum efficiency (EQE), along with high reproducibility.