The invention relates to hyperbranched 
polyamino acid. The 
chemical composition is as follows: in the formula of (Lys-)a-(-Arg-)b-(-His-)c-(-X)d, Lys, Arg and His are respectively 
lysine, 
arginine and 
histidine, X is one of or a plurality of any amino acids except for the amino acids above, wherein a is not less than 0.2 and not more than 0.95, b is not less than 0 and not more than 0.8, c is not less than 0 and not more than 0.8, d is not less than 0 and not more than 0.3, and the sum of a, b, c and d is 1. The preparation method is as follows: uniformly mixing 
lysine or 
lysine salt with other amino acids or the 
amino acid salts contained in the hyperbranched 
polyamino acid to react for 2-64h at the temperature of 130-180 DEG C and then obtain yellow 
solid, and finally purifying the coarse product with a 
precipitation method to obtain the hyperbranched 
polyamino acid. The hyperbranched polyamino acid obtained in the invention can be used as nonviral 
gene carrier for the transduction of huamn or animal 
cell gene, and the hyperbranched polyamino acid nonviral 
gene carrier provided by the invention is reasonable in design, simple in preparation method, high in 
transfection efficiency, low 
cytotoxicity and favorable transduction efficiency in the presence of 
blood serum.