Abstract: Paleozoic traps of Bozhong 21-2 tectonic zone are controlled by faults and up dip pinchout. In the process of lithology boundary description, pinchout line explanation has multi-solutions and it brings difficulty for explaination. In order to get the pinchout line for more accurately describing carbonate formation, a more actual explaination method should be seeked to confirm structure size and reserve scale. In practical work, by considering carbonate formation seismic reflection characteristics and sedimentary characteristics, forward simulation has been carried out in the area to provide guidance for pinchout line explaination. By using the seismic attribute technology and forward simulation technology, the forward simulation of typical seismic profiles has been modeled, and then seismic reflection pinchout point and geological pinchout point have been summarized so as to describe the lithology boundary.