Objective To investigate the expression of tyrosine kinase B (trkB) protein and mRNA in hippocampus of mouse during persistence of spatial memory in Morris water maze. Methods Twenty-eight C57BL/6 mice were divided into test group (n=14) and control group (n=14). MWM were performed on mice in test group, which included four trail days and one probe day, and mice in control group only experienced one probe day. During trail days, the latencies, swimming distances and swimming velocities were recorded. On probe day, the times across platform and time percent during platform quadrant were recorded. All mice were sacrificed after probe, and hippocampi were dissected for determination of contents of trkB protein and expression of trkB mRNA by ELISA and Real-Time RCR respectively. Results During trail days, the latencies and swimming distances of mice in test group decreased after repetitive training (P<0.05). On probe day, the times across platform and time percent during platform quadrant in test group were significantly higher than those in control group (P<0.05). There was no significant difference in the expression of trkB protein and mRNA in hippocampi between test group and control group (P>0.05). Conclusion Long-term spatial memory of mouse is established in Morris water maze, but the content of trkB is not upregulated during persistence of spatial memory.