This study investigates the vibration characteristics of planetary gear transmissions subjected to pitting faults. Gear contacts are modeled using the Hertzian contact theory, and multi-flexible body dynamics models are established and simulated for gears in healthy, mild, moderate and severe states of pitting damage. The time-frequency domain vibration responses of planetary gears are analyzed under these different conditions of pitting corrosion. A vibration test platform for planetary gearboxes is built to capture the vibration response signals, which are used to verify the accuracy and reliability of the dynamic model of pitting-induced vibrations. The results show that both the effective and peak-to-peak values of vibration velocity in the Y-direction increase with the severity of the pitting damage. The vibration velocity and acceleration of the slightly corroded model show distinct sideband frequencies, and the experimental results are basically in agreement with the simulation results. Additionally, the study identifies variations in the width and depth of micro-pitting and macro-pitting during their expansion.