A method for preparing chimeric antigen receptor -carrying exosomes derived from immune cells wherein the immune cells are T cells or NK cells, comprising the following steps: A) preparing the CAR expressing immune cells by a general bioengineering technology; B) antigen-specific activation of the CAR expressing immune cells: soluble recombinant specific targets, engineered cells expressing the specific targets, or tumor cells expressing the specific targets are adopted as activating agents; wherein the specific targets are antigen targets targeted by a single-chain fragment variable (scFv) expressed by the CAR expressing immune cells; adding an antigen protein or an immobilized antigen protein to an in vitro culture system, directly co-cultivating the CAR expressing immune cells with inactivated engineered cells expressing the specific targets, or with inactivated tumor cells expressing the specific targets, to obtain antigen-specific activated CAR expressing immune cells; C) isolation of exosomes of the CAR expressing immune cells: collecting a culture supernatant of the antigen-specific activated CAR expressing immune cells, and isolating the exosomes by a general exosome isolation method to obtain an exosome suspension; D) adding magnetic beads coated with a specific antigen (namely, CAR-capturing magnetic beads) to the exosome suspension obtained in step C, wherein, the magnetic beads comprise a recombinant target protein antigen that can specifically bind to the CAR protein; incubating a resulting suspension, and then placing the suspension in a magnetic field; removing the supernatant, and then adding a buffer; adding the resulting suspension to a column, eluting the exosomes retained on the column with buffer, wherein, after the supernatant is added to the column, substances flowing out first are exosomes without the antigen binding ability, and then the column is rinsed with buffer to obtain the CAR-carrying exosomes derived from immune cells that have the antigen binding ability; depending on a volume of an initially collected medium, adding PBS as appropriate to resuspend exosomes; detecting a total protein concentration with Bradford kit; and dispensing and storing the resulting exosomes at -80°C. A) preparing the CAR expressing immune cells by a general bioengineering technology; B) antigen-specific activation of the CAR expressing immune cells: soluble recombinant specific targets, engineered cells expressing the specific targets, or tumor cells expressing the specific targets are adopted as activating agents; wherein the specific targets are antigen targets targeted by a single-chain fragment variable (scFv) expressed by the CAR expressing immune cells; adding an antigen protein or an immobilized antigen protein to an in vitro culture system, directly co-cultivating the CAR expressing immune cells with inactivated engineered cells expressing the specific targets, or with inactivated tumor cells expressing the specific targets, to obtain antigen-specific activated CAR expressing immune cells; cells; adding an antigen protein or an immobilized antigen protein to an in vitro culture system, directly co-cultivating the CAR expressing immune cells with inactivated engineered cells expressing the specific targets, or with inactivated tumor cells expressing the specific targets, to obtain antigen-specific activated CAR expressing immune cells; C) isolation of exosomes of the CAR expressing immune cells: collecting a culture supernatant of the antigen-specific activated CAR expressing immune cells, and isolating the exosomes by a general exosome isolation method to obtain an exosome suspension; D) adding magnetic beads coated with a specific antigen (namely, CAR-capturing magnetic beads) to the exosome suspension obtained in step C, wherein, the magnetic beads comprise a recombinant target protein antigen that can specifically bind to the CAR protein; incubating a resulting suspension, and then placing the suspension in a magnetic field; removing the supernatant, and then adding a buffer; adding the resulting suspension to a column, eluting the exosomes retained on the column with buffer, wherein, after the supernatant is added to the column, substances flowing out first are exosomes without the antigen binding ability, and then the column is rinsed with buffer to obtain the CAR-carrying exosomes derived from immune cells that have the antigen binding ability; depending on a volume of an initially collected medium, adding PBS as appropriate to resuspend exosomes; detecting a total protein concentration with Bradford kit; and dispensing and storing the resulting exosomes at -80°C.