The depositional basin often has two or more than two temperature-pressure systems,including one temperature-pressure system of shallow-formation and one or more than one temperature-pressure systems of deep-formation.The temperature and the formation pressure keep the line relationship in the same temperature-pressure system,but in different temperature-pressure systems,the line slope of temperature-pressure relationship is different.The authors analyse Moliqing Sag's temperature pressure system characters in Yitong Graben.There are two superimposed temperature-pressure systems in the shallow and deep formations of Molingqing Sag.The deep one is prone to high pressure.It is also showed that Shuang yang Group, the west of Moliqing Sag, is the low temperature and high pressure zone; the northwest is the low temperature and low pressure zone; Maanshan fault belt is the normal temperature and normal pressure zone;Jianshan uplift fault belt is the high temperature and low pressure zone. The vertical and planar distribution characters of temperature-pressure systems have some influences on the formation and distribution of petroleum pool.