The invention provides a preparation method of bispecific 
chimeric antigen receptor gene modified natural killer cells, comprising the features: constructing a bispecific 
chimeric antigen receptor gene containing specific-binding signaling 
lymphocyte activation molecule family member 7 and 
fibronectin mutants, recombining the bispecific 
chimeric antigen receptor gene to a 
viral vector, transfecting with human natural killer cells, and highly expressing the bispecific chimeric 
antigen receptor gene, thus specifically binding 
tumor cells that express the signaling 
lymphocyte activation molecule family member 7 and 
fibronectin mutants, inhibiting expression of 
natural killer cell inhibitory receptors, and preventing 
immune escape of 
tumor cells; meanwhile, activating a first 
signal and a co-stimulatory 
signal to trigger toxic activity of the 
tumor cells, and great anti-tumor killing 
toxicity is shown in in-vivo and in-vitro experiments; the invention also provides a kit for the preparation of autologous natural killer cells through the above method, and with the kit, it is possible to highly express the bispecific chimeric 
antigen receptor gene and trigger great anti-tumor effect.