Abstract: Many achievements have been made in studying the tectonic evolution of Ailao Mountain-Red River fault zone by using isotopic chronology, but the thermal history evolution process has not been constructed from the low-temperature to high-temperature system. And the controversy exists in the starting time of the left-lateral strike-slip of the fault zone. The age data in the south central section of Ailao Mountain-Red River fault zone were summarized, and the age values from the same isotopic system turned to be younger from the southeast to the northwest, with less differences. The study area is divided into: north, middle and south section section, and T-t change curve is constructed using the low, medium and high temperature ages. The thermal history evolution shows that the fault zone has experienced two stages of cooling history. The temporal and spatial changes of cooling rate and uplift and denudation rate recorded the transmission of tensile strain from southeast to north, with gradually weakening of transformation tensile strength and fault activity during the transmission process. The activity process of the fault zone is finally divided into three stages: The immediate left walking sliding stage (35-20 Ma), The gradual stop stage of left-handed slipping (20-6 Ma), and the right-handed slipping stage (6 Ma to the present). The fault tectonic activity reflects the continuous adjustment process of the stress in the southeast margin of Qinghai-Tibet Plateau during the India-Eurasian plate collision.