Objective To establish a BALB/c mouse model infected with tick-borne encephalitis virus (TBEV) via intraperitoneal injection, and observe the infection symptoms and replication characteristics of TBEV in mice. Methods Six-week-old female BALB/c mice were randomly assigned (1:1:1) to control group, 1×10³ plaque-forming unit (PFU) TBEV infected group (infected by intraperitoneal injection of 1×10³ PFU per mouse), or 1×10⁴ PFU TBEV infected group (infected by intraperitoneal injection of 1×10⁴ PFU per mouse). The infection symptoms, body weight changes, and survival rates of the mice were monitored. The pathological changes in the brain and spleen of the mice were observed by hematoxylin-eosin (H-E) staining. The expression of TBEV protein in the brain and spleen of the mice was detected by immunohistochemistry. The dynamic changes of TBEV titers in the brain and spleen of the mice were detected by plaque assay. Results The infected mice developed arched back and hind limb paralysis on day 6 in the 1×10⁴ PFU TBEV infected group and on day 7 in the 1×10³ PFU TBEV infected group. Compared with the control group, the body weight of mice was significantly decreased from day 5 in the 1×10⁴ PFU TBEV infected group and from day 6 in the 1×10³ PFU TBEV infected group (P<0.05). The mice died from day 7 post-infection, and all died on day 8 in the 1×10⁴ PFU TBEV infected group and on day 9 in the 1×10³ PFU TBEV infected group. The H-E staining results showed that on day 5 and 7 after TBEV infection, only a small amount of neuronal nucleus pyknosis and deep staining were observed in the brain cortex of the mice, and no infiltration of inflammatory cells was observed. On day 5, the red pulp of spleen showed mild congestion and neutrophils; on day 7, neutrophils were increased. The immunohistochemical staining results showed that TBEV protein was expressed in the brain and spleen of mice on day 5 after TBEV infection, and was increased on day 7. On day 7 post-infection with 1×10³ PFU TBEV, TBEV titers were (1.3±0.6)×10⁵ PFU/mL in the brain of mice and (1.3±0.6)×10³ PFU/mL in the spleen. Conclusion A BALB/c mouse model infected with TBEV has been successfully established by intraperitoneal injection, and TBEV can proliferate and be pathogenic in mice.