The invention discloses a primary microglial cell/injured neuron co-culture system and a construction method and application thereof. The system comprises primary microglial cells and injured neurons,wherein the injured neurons are swallowed by the primary microglial cells intracellularly; and the system is an in vitro co-culture system. According to the primary microglial cell/injured neuron co-culture system disclosed by the invention, compared with the disadvantages of resting microglial cells cultured by a traditional method, the microenvironment of nerve injury is simulated to activate the microglial cells, and the phagocytic function of the microglial cells is maintained; the microglial cells inside the system can be activated into macrophagocytes by the injured neurons, so that thephagocytic capacity of neuron fragments is strengthened; in the system constructed by the method, the primary cells are considerable in quantity, stable in characteristics and relatively high in activity, and the reliable co-culture system can be provided for subsequent fundamental research of nerve injury or degenerative diseases.