Objective To observe the expression changes of sodium channel Nav1.8 in dorsal root ganglion (DRG) and thalamus of rats with tibial cancer pain caused by Walker256 mammary gland carcinoma cells and explore the correlation of Nav1.8 and cancer pain. Methods Wistar rats were randomly divided into the bone cancer pain group (n=15) and sham-operation group (n=15). The bone cancer pain model was established by injecting the Walker256 mammary gland carcinoma cells of 107/mL into the tibia medullary cavity of rats of the bone cancer pain group. The tibia medullary cavity of rats of the sham-operation group was injected with the same volume of normal saline. The mechanical withdraw threshold and paw withdrawal thermal latency were assessed 8, 11, 14, 17, and 21 d after surgery. Imaging examination was conducted 21 d after surgery and DRG and thalamus of rats were collected. Expression changes of Nav1.8 mRNA in DRG and thalamus were observed by the real-time PCR. The protein expression of Nav1.8 in DRG was detected by the immunofluorescence method. Results The mechanical hyperalgesia of the bone cancer pain group was significant at each time point after surgery. Compared with sham-operation group and before surgery, the differences of mechanical withdraw threshold were statistically significant (P<0.05). The paw withdrawal thermal latency of the bone cancer pain group did not change significantly after surgery. The differences of paw withdrawal thermal latency of the sham-operation group and bone cancer pain group after surgery and before surgery were not statistically significant (P>0.05). The mRNA expressions of Nav1.8 in operation homolateral DRG and operation contralateral thalamus were significantly increased (P<0.05). The differences of mRNA expressions of Nav1.8 in operation contralateral DRG and operation homolateral thalamus of the bone cancer pain group and sham-operation group were not statistically significant (P>0.05). Conclusion The up-regulation of Navl.8 expression is relevant to the incidence of bone cancer pain of rats.