The recognition of unconformities and their vertical structures is of significance for understanding the tectonic history and petroleum accumulation regularities in the place w:st="on">Junggar Basinplace>. According the analysis of tectonic background, outcrops, compound loggings and seismic data, it has a conclusion that there are four types unconformities:onlap/erosion truncation type, concordance/erosion truncation type, onlap/concordance type, concordance/concordance type. Four important unconformity surfaces were identified and analyzed. The unconformities in the compressional abdominal area are not only the important paths for the oil and gas migration, but also are the favorite place for the oil and gas accumulation.