Objective To investigate the Tbr1’s role during the development of neocortex and hippocampus. Methods The brains of Kunming mice from embryonic day 16.5 (E16.5) to postnatal day 14(P14) were used for immunofluorescent staining to visualize the expression of Tbr1 in neocortex, entorhinal cortex and hippocampus. Fifty-two mice (8-10 mice in each age group) were used for this study. Results 1. Tbr1’s expression was mainly located in cortical plate of neocortex and entorhinal cortex, especially in the cortical subplate or layer Ⅵ of cortices above; 2. In the dentate gyrus, Tbr1 positive cells were located in the granular layer, and were found innergranular layer after P7; 3. According to their location and histogenesis, the Tbr1 positive cells were the migrating and newborn neurons in the cortical plate. Conclusion Tbr1 plays a key role in cell migration and neural differentiation during cerebral development. As a marker of newborn neuron, Tbr1 is involved in the cortical lamination and affects the processes of cell migration and neural differentiation.