The invention relates to an ultra-short pulse self-correlation measuring device and method. The device comprises a first collimating lens and a half-wave plate, a polarization beam splitter prism, a first reflector, a controllable delay reflector, a chopper and a second reflector, a second collimating lens, a carbon nanotube saturated absorber film, a photomultiplier, a phase-locked amplifier anda computer. Through a simple structure, the ultra-short pulse width measurement with low power and low energy can be realized.