This review article summarized the relationship between inflammation and depression as well as several pathways of neuroinflammation affecting depression, such as neuroinflammation can affect the synaptic availability of monoamine neurotransmitters and Glu, increase the activation time of the HPA axis, regulate the BDNF/TrkB signaling pathway in various brain regions. This evidence concerns the gene NTRK2 and major depressive disorder.