Terahertz waves are located in the energy level range of hydrogen bonding and van der Waals forces, and can directly couple with proteins to excite the nonlinear resonance effect of proteins. Therefore, terahertz wave can affect the conformation of proteins, the structure and function of neurons. Primary cerebral cortex neurons of SD rats are cultured in vitro. Neurons are radiated 3 days by THz wave with 0.3–3.0 THz in frequency and 100 μW in power; the growth and development indicators of neurons (Cell body area, total length of process) are recorded. At the end of a radiation programme, Western blotting is used to detect the protein expressions of GluA1, GluN1, postsynaptic density protein-95 (PSD-95) and synaptophysin 38 (SYP-38). After the first day of terahertz wave radiation, the cell area is increased by 144.9% ( P< 0.05); on the second day and third day of terahertz wave radiation, the growth value of the total length of neuronal neurites are increased by 65.1% ( P< 0.05) and 109.4% ( P< 0.05), respectively. After the three-day terahertz wave irradiation, the protein expressions of GluA1 and SY-38 are increased by 38.1% ( P< 0.05) and 19.2% ( P< 0.05), respectively. In addition,some results show below. 1) The use of low-intensity broadband terahertz wave in this study will not cause the cortical neurons to die, and will not affect their regular growth. 2) Low-intensity broadband terahertz radiation can promote the growth of cortical neuron cell bodies and processes, but the effects on cortical neuron cell bodies and processes are different. This may be related to the developmental cycle of cultured cortical neurons in vitro, and there is a cumulative effect on the promotion of neuronal processes by low-intensity broadband terahertz. 3) The promotion of neuronal growth and development by low-intensity broadband terahertz wave radiation may be related to the proportion of AMPA receptor subtypes and the expression of presynaptic specific protein SY-38. These results herald a specific-frequency and specific-energy terahertz radiation can be developed into a novel neuromodulation technology for the treatment or intervention of diseases such as neurodevelopmental disorders.