The basins of foreland thrust belts in the central and western China has experienced four stages of deposition evolution，namely craton deposition, early foreland deposition, Mesozoic depression basin deposition and Cenozoic regeneration foreland basin deposition. There have developed four types of caprock, namely Kraton or transitional facies caprock, limnetic facies coal measure caprock, oxidation basin valley or adjacent marine facies cream mudstone caprock，and lacustrine mudstone caprock. Quantitative and comparative analysis of caprock lithology, accumulation thickness, thickness ratio of caprock to total strata, thickness of individual layer, lithomechanics characteristics and hydrocarbon column sealed by caprock of three types of foreland basin, i.e. folding (southern Jungar basin), alternation (western Sichuan basin) and anagenesis (northern margin of the Qaidam basin), indicates that the sealing ability of western Sichuan basin is better than that of southern Jungar basin, the sealing ability of southern Jungar basin is better than that of northern margin of the Qaidam basin, the quality of caprock of Youshashan group up and down of northern margin of the Qaidam basin Pliocene is bad, the sealing ability of Taxihe group of southern Jungar basin Miocene , Shangancaigou of Oligocene and Lulehe group Eocenef northern margin of the Qaidam basin is good, and the rest are best. The caprocks with the best quality are located in the association of reservoir and caprock of Ⅱ (T3 —J association of foreland basin or continental depression basin) and Ⅲ (J3 —P Molass e association of intracontinental depression). The associationⅡ is Mesozoic coal measure caprock of limnetic facies, which controls the accumulation and reservation of self-generation and self-reservation of original hydrocarbon reservoir； the association Ⅲ is Tertiary mudstone caprock of oxidation basin valley or adjacent marine facies cream, which plays an important part in sealing the oil and gas that is linked to hydrocarbon source rock underlying the faults, or is adjusted to the association Ⅲ. Controlled by best quality caprock, the oil and gas mainly concentrate in the association of reservoir and caprock ofⅡand Ⅲ in the foreland basin of the central and western China.