Human Immunodeficiency Virus (HIV) infection is a chronic infectious and fatal disease that directly attacks the central nervous system, killing the body’s helper T lymphocytes and CD4+ T cells, increasing the body’s susceptibility to life-threatening opportunistic infections, and causing rare cellular immunodeficiency diseases such as Pneumocystis carinii pneumonia and Kaposi’s sarcoma. The direct invasion of the central nervous system by HIV leads to HIV encephalopathy. Neuropathological changes may include neuronal reduction, multinucleated giant cells, microglia nodules, diffuse astrocyte proliferation, white matter vacuole formation, and demyelination. The disease mainly involves the basal nucleus and subcortical white matter, while the gray matter of the cerebral cortex is less affected. HIV-infected patients are prone to a variety of psychiatric disorders, either primary or secondary. Primary complications are caused by HIV directly invading the central nervous system or HIV destroying the immune system; secondary complications are caused by opportunistic infections, tumors, cerebrovascular diseases caused by HIV infection and side effects of drug treatment. The psychological and social factors of patients can also affect the occurrence and development of psychiatric symptoms. The main manifestations are as follows: 1. Mild cognitive dysfunction Patients show difficulty in concentration, delayed reaction and mild cognitive deficits, but there is no serious impairment in daily life functions. 2, HIV infection dementia (HIV dementia) about 10%-20% of AIDS patients can be accompanied by dementia. Dementia usually appears late in the disease, especially when the patient’s immune system is severely suppressed. HIV infection with dementia is usually a sign of poor prognosis, and about 50%-75% of patients die within 6 months of the onset of dementia. The clinical presentation is predominantly subcortical dementia, but in the late stages of the disease, patients may develop typical cortical symptoms such as aphasia and apraxia, and may be accompanied by motor retardation, clumsiness, and gait instability. 3.Delirium Etiology includes HIV infection in the brain, drugs used to treat AIDS, and secondary infections. Patients may show anxiety, depression, suicidal behavior in severe cases, and manic-like and schizophrenic-like symptoms. For HIV dementia, antiretroviral drugs, such as zidovudine (AZT) and other adjuvant drugs can be used clinically; those with psychiatric symptoms can be treated symptomatically.