In this article, a photonic scheme based on dual-drive dual-parallel Mach-Zehnder modulator (DD-DPMZM) to generate switchable dual-band dual-chirp microwave waveforms is proposed and experimentally demonstrated. In the scheme, the switching among two single-band dual-chirp signals and a dual-band dual-chirp signal can be readily realized by simply adjusting the bias voltages on the modulator. Theoretical analysis on the operation of the approach is presented. Full experimental verification on the generation of switchable dual-chirp signals in the S-band and C-band has been successfully demonstrated. The presented scheme features in the simple structure, easy tunability and reconfigurability, which has potential applications in multi-band radar.