Fission track ages (FTA) and track lengths of apatite from Qing-He diorite intrusion in Altay Mountains are measured. Apatite fission track ages of three diorite samples is range from (78±5) Ma to (95±5) Ma

and the lengths of horizontal confined spontaneous fission tracks are (13.2±1.2)—(13.5±1.3) μm. The distribution of the track length is narrow and symmetrical with a mean length of approximately 13.3 μm and a standard deviation of around 0.1 μm. The inverse modeling results show that thermal history of this region has four stages

two rapid uplift stages and two stable ones. The rapid uplift during the 115—85 Ma with the cooling rate of 2.2 ℃/ Ma suggests that this region still existed magmatic intrusion and tectonic movements in Yanshanian.