The invention provides a multi-focal double-contrast tube. The multi-focal double-contrast tube comprises a cathode emitter (1) and an anode target plate (2), which are oppositely arranged along the advancing direction of electron beams; two magnetic quadrupole lenses (3), which are same in shape and size and opposite in polarity, are arranged between the cathode emitter (1) and the anode target plate (2) in parallel along the advancing direction of the electron beams; the magnetic quadrupole lenses (3) are provided with multiple magnetic poles (31); furthermore, the magnetic poles of the twomagnetic quadrupole lenses (3) are oppositely arranged with each other; each magnetic pole (31) is wound with an exciting coil (32) used for generating a focusing magnetic field and capable of changing the Ampere turns; and the focal length of the two magnetic quadrupole lenses (3) is adjusted by changing the Ampere turns of the exciting coil (32). According to the multi-focal double-contrast tubeand a control method thereof provided by the invention, in the original size focal mode, in coordination with a micro-focal imaging algorithm, micro-focal phase-contrast imaging on a key small area is realized; development of CT clinical diagnosis is greatly promoted; and the engineering applicability is very high.