The invention discloses a preparation method and use of a 
thioctic acid-modified 
polyethylene glycol-polyaminoacid amphiphilic triblock 
copolymer. A hydrophilic chain of the amphipathic triblock 
polymer is 
polyethylene glycol, a middle hydrophobic 
chain segment of the amphipathic triblock 
polymer is poly(benzyl glutamate), a 
tail hydrophobic 
chain segment of the amphipathic triblock 
polymer is polyphenylalanine and the 
side chain of the middle 
chain segment is modified through 
thioctic acid. The amphipathic triblock polymer is self-assembled in water to form a polymer nanometer 
micelle with 
polyethylene glycol as an outer crown, 
thioctic acid-modified poly(benzyl glutamate) as a middle shell and polyphenylalanine as an inner core. Through crosslinking of the nanometer 
micelle, the stable reduction-sensitive shell crosslinked nanometer 
micelle is obtained so that the nanometer micelle is not easily dissociated 
in vitro and in blood and thus stability of a nanometer micelle-coated 
drug is guaranteed. When the nanometer micelle enters a tumor 
cell, the nanometer micelle can be fast crosslinked and dissociated so that the 
drug can be fast released and produces high treatment effects. The amphipathic triblock polymer solves the problems of 
drug leakage 
in vivo, low conveying efficiency and slow release in cells.