The invention provides a preparation method of a transmission
electron microscope ultrathin sample with a cross section of an
electron beam sensitive material, which comprises the following steps: selecting a specific region as a to-be-extracted sample region for the
electron beam sensitive material by adopting an electron beam
imaging technology; depositing a protective layer on the surface of the to-be-extracted
sample area by adopting an electron beam and / or an
ion beam; bombarding a to-be-extracted
sample area by utilizing a high-energy
ion beam, extracting an electron beam sensitive material cross
section sample from the to-be-extracted
sample area, and fixing the extracted sample to a
metal bracket; performing pre-
thinning treatment on the extracted sample by using a
focused ion beam to obtain a first thinned sample of which the thickness is reduced to be less than a first thickness; and transferring the first thinned sample into a micro-beam fixed-point
ion thinning system, and carrying out multi-time stepped low-energy
ion beam fine
thinning treatment on the first thinned sample by using
inert gas ion micro-beams to obtain a second thinned sample which is clean in surface and free of a surface ion damage layer and has the thickness reduced to be less than a second thickness, and taking the second thinned sample as a transmission
electron microscope ultrathin sample.