A shock-accelerated flying foil is diagnosed with a chirped pulse spectral interferometry. The shock is pumped by a 1.2ps chirped laser pulse with a power of～1014 W/cm2 at 785nm irradiating on a 500nm aluminium film and detected by a probe pulse split from the pump based on a Michelson spectral interferometry. A flying foil of～5.595×10-6 g in～400 μm diameter was accelerated to～165 nm away from the initial target rear surface at～1.83 km/s before ablation.