The exhumation mechanism of the low-temperature/high-pressure (LT/HP) rocks, is critical for understanding the formation of the central Qiangtang metamorphic belt (CQMB), Tibetan Plateau, but it is still hotly debated. Here, we report field, petrological, phase-equilibria and petro-physical modelling data on the newly discovered lawsonite-bearing eclogites, epidote eclogite and lawsonite-bearing blueschists from the Lanling area in the CQMB. The mineral characteristics and phase equilibria modeling reveal that the LT/HP rocks record peak P-T conditions from peak pressure (P_max) of 22.5–23.5 kbar at 460–480 °C to peak temperature (T_max) of 530–550 °C at 20–22.5 kbar. Combined with previous documented geochronological data, a clockwise P-T-t path for these LT/HP rocks is obtained, which is characterized by pronounced heating decompression (~223–221 Ma), subsequent isothermal decompression (~221–219 Ma), and final cooling decompression (~219–212 Ma). Modeled densities and net buoyancies (defined as the density difference between Preliminary Reference Earth Model and LT/HP rocks) show that all LT/HP samples are buoyant at P_max, but gradually become denser during heating decompression and evolve to neutrally or negatively buoyant around T_max. Later mixing with lower-density garnet-phengite schists at T_max, help the density of the exhuming LT/HP unit reduce to lower than that of the surrounding mantle again during continued isothermal decompression. We concluded that exhumation of eclogites and blueschists is short-lived (~10 Ma) and multi-stage buoyancy-driven characterized by early self-exhumation via diapiric rise and post-T_max carried-exhumation along subduction channel.