Abstract: A construction method for an immunodeficient rat model includes the following steps. The gRNAs targeted for knocking out a Prkdc gene and an IL2R? gene are mixed with CAS9 mRNA respectively, and frozen in RNase-free ultrapure water to obtain injections A and B correspondingly. A human SIRP? genomic DNA is amplified, purified, and frozen in RNase-free ultrapure water to obtain an injection C. The injections A and B are injected into cytoplasm of fertilized eggs of different rats, and the injection C is injected into a pronucleus of a fertilized egg of another rat. The three fertilized eggs are then transplanted into different pseudo-pregnant female rats to breed second-generation rats A, B and C, respectively. The second-generation rats A, B and C are intercrossed to breed an F1 generation; and the F1 generation is further intercrossed to obtain IL2R? and Prkdc gene knockout immunodeficient rat models with human SIRP? gene.