Abstract: The Jurassic oil traps of the Yan'an Formation in the Block Q of the Erdos Basin is a structure and lithology controlled hydrocarbon reservoir. It is narrow in width and strong in anisotropy. Therefore, it is difficult to define the distribution pattern of the sand body and the low amplitude of structure only by the approach of drilling. In order to solve this problem, 3D seismic technique is used and this paper aims to illustrate the concrete steps of the 3D seismic survey. With the advantages of high lateral resolution and the continuity of the 3D seismic technique, a series measures, such as fine horizontal calibration, velocity analysis, reflection configuration recognition and inversion, are applied to the fine prediction of strata, fractures, and other reservoir forming factors. All these measures have provided strong technical support to the decision of well locations.