The control factors of petroleum accumulation in Baijiahai swell of Junggar basin are discussed in terms of oil/gas source, trans-port system and paleo-structural evolution, etc. The results show that the oil/gas source originated from the Permian hydrocarbon source rock, the Jurassic coal-measure source rock and both of them; the fault/fractures, structural ridge-sand body are as the favorable transport system; the multi-migration and changes occurred in its geological history period for the paleo-structural highs in this swell, and the reser-voirs discovered nowadays are mainly distributed along these highs. When hydrocarbons in the source rocks were generated and expelled, the opened fractures and sand bodies became the preferred oil/gas migration pathways until the oil/gas entered into the paleo-highs. And the paleo-traps were seldom influenced by late tectonic movements. Therefore, the present reservoirs in this area are all characterized by their distributions along the paleo-highs.