Abstract: In Yuanba area of the northeastern Sichuan Basin,vitrinite reflectance and(U-Th)/He dating analyses of apatite and zircon in chip samples from the Xujiahe(T₃x)-Jiading(K₁j) Formations were carried out.A dynamic evolution model based on He age and depth/temperature was set up,by means of which we concluded that the He closure temperature of apatite was about 95℃.Most of the Mesozoic strata(T₃x-K₁j) in the study area experienced the He closure temperature of apatite(95℃) while no sample experienced the He closure temperature of zircon,and some samples from T₃x²-J₁z underwent the maxium palaeogeothermal of about 170℃.From Paleogene to Neogene(0.2-36.4 Ma),the Mesozoic strata in Yuanba area went through a severe cooling uplift and denudation with the denudation rate of 109.9 m/Ma.In K₁j and the overlying strata,the maximum denudation thickness was about 4000 m.The dynamic thermal evolution history in the study area was illustrated systematically as followed.In Mesozoic,the maximum palaeogeothermal of strata was 170-190℃.As strata upraise,palaeogeothermal decreased.From 36 to 176 Ma,palaeogeothermal was 95-170℃.From 0 to 36 Ma,the present geotemperature is below 95℃.