The invention relates to a method for preparing polyepitope chimeric gene vaccines, designated as Epitopes Assemble Library Immunization (EALI). It involves the construction of expression libraries of polyepitope chimeric genes with different sizes and lengths using gene shuffling and random assembly so as to screen polyepitope chimeric gene vaccines. Immunization of the body with the gene libraries of the invention results in the induction of high level of specific antibodies and specific types of cytokines, and protection on the body.