The third generation window period mainly refers to the detection of HIV virus antibody through the third generation testing means, and its window period mainly refers to 3~12 weeks after high-risk contact. HIV virus is mainly transmitted through sexual transmission, generally condoms can block the transmission of the virus, the window period mainly refers to the gradual proliferation of antibodies after infection with the virus, antibody titers gradually increase, when suspected of exposure to HIV virus, general hospitals are currently through the third generation of detection means, so in the 3-12 weeks after the exposure is prone to false-negative results, but after 12 weeks of the test results are more accurate. AIDS belongs to the immune system disease, manifested by generalized lymph node enlargement, fatigue, weight loss and other symptoms, at present, mainly through sexual transmission, we must pay attention to protect themselves, pay attention to hygiene, avoid unclean sexual intercourse.