To study oil-gas accumulation law, based on the study of development and distribution of caprocks and its controlling to oil-gas accumulation and distribution in Fangzheng depression were studied by the method analyzing matching between faults and caprocks and relation between it and oil-gas distribution. The result indicates that there are two types of matching between faults an caprocks which caprock is faulted fully and caprock is not faulted fully. The former is showed in Xin"ancun+Wuyun formation in the west of depression. The latter is showed in the first and secondary member of Baoquanling formation, bottom of Xin"ancun Wuyun formation. Controlling of matching between faults and caprocks is shown in following three aspects: 1.oil-gas distributes over and lower of caprock in matching between faults and caprocks which caprock is faulted fully; 2.oil-gas only distributes lower of caprock in matching between faults and caprocks which caprock is not faulted fully; 3.difference of matching between faults and caprocks controls difference of oil-gas distribution in the east and in the west of depression.