Northwestern Sichuan locates the north of Songpan-ganzi orogenic zone. In this region, many granite bodies and Carlin type gold deposits formed in Mesozoic. The gold ore-forming process has close relation with the tectonic movement and the magmation. This paper will analyze this problem by granite. Yanggonghai monzonitic granite body, Dagaizhai monzonitic granite body and Ke’eryin two-mica granite body have been dated by Ar-Ar with biotite and muscovite, and their plateau ages are 158.7±1.4Ma, 185.2±1.4Ma and 157.6±1.2Ma respectively. Base on these Ar-Ar ages and other early ages dated by other isotope system, the cooling tracks of main granite bodies in different location have been drawn. The cooling tracks show that from the northern orogenic zone to the center of eastern orogenic zone, the intruding ages become younger, cooling rates become lower, and in the stable stage of orogenic process the cooling rates become little. From these features, we can deduce that during the orogenic process, the tectonic stress transferred from border to interior gradually from north to south. Finally, all tectonic units come to pediocratic stage of orogenic process. In the pediocratic stage, tectonic movement is weak, the cooling rate of granite bodies is little, and the crust keep low temperature state for long time, which is benefit for gold deposit to form. Thus, most gold deposit in northwestern Sichuan formed in the low cooling rate stage, which may be a reason for the coupling relation between granite and gold deposit.