The invention belongs to the technical field of biomedicines and in particular relates to 
protein nanoparticles carrying an antitumor 
peptide and a preparation method and application of the 
protein nanoparticles. The preparation method comprises the following steps: according to 
gene sequences of a pET25b(+)-HSP16.5 
expression vector, synthesizing a single stranded 
DNA (deoxyribonucleic acid) sequence corresponding to an 
apoptosis-promoting 
peptide, namely KLAK 
peptide, performing annealing treatment, performing 
HindIII and 
XhoI double-
digestion on the product and the vector, performing gel recycling on the 
digestion product, connecting the KLAK sequence with the vector, transforming the connection product into a competence of DH5a 
escherichia coli, picking a 
monoclonal bacterial colony, performing overnight bacterium shaking, extracting a 
plasmid, and performing sequencing; and transforming a pET25b(+)-HSP-KLAK 
plasmid with correct sequencing into a competence of BL21 
escherichia coli, amplifying culture, performing ultrasonic bacterium crushing so as to obtain a corresponding crude product, performing purification, and performing 
dialysis, concentration and freeze-
drying, so as to obtain an HSP-KLAK 
protein. The 
heat shock protein nanoparticles carrying the antitumor peptide, which are provided by the invention, can be rapidly taken in by 
tumor cells, after being released inlysosome, a targeting 
mitochondrion plays a role of tumor killing, the protein of the 
medicine carrier self can be rapidly degraded by cells, and thus a good tumor 
treatment effect can be achieved.