Based on domestically-made devices, a small 2000 W pulsed power amplifier working at L-band is developed in this paper. The key design process and test results of the power amplifier are presented, the scheme of negative voltage protection and balanced power combining of the power amplifier are discussed. The power amplifier has the features of small volume , high efficiency and high reliability because of using a novel double-deck cavity structure, GaN device, and a balanced power combining.