Abstract: During the halfgraben lacustrine basin developed, the episodic differential subsidence controlled by the main fault in steep slope zone of the lacustrine basin will result in the accommodation redistributed. While the water redistributing, the change of the relative lake level is not even at each point in lacustrine basin and the parasequence sets are also different. The concept of the accommodation transform hinge of half-graben lacustrine basin is put forward. The mathematic model of the accommodation transform hinge is built theoretically. The distributing position of the accommodation transform hinge and the influence factors are discussed. If it is located under the accommodation transform hinge in the gentle slope zone, the depth of water becomes deeper and forms TST(transgressive system tract); on the contrary, the water becomes shallow and forms RST(regressive system tract). HST(highstand system tract) will be formed in the tranquility period. The conception can help researchers study the uneven change of the relative lake level in half-graben lacustrine, and it is also helpful to find subtle reservoirs.