Fluvial pattern is not only a basis problem in river dynamics and river engineering, but also a key problem for sedimentologists to identify different types of sandstone. Currently, most classifications of fluvial channels are based on the plan view morphology and while these classifications have received more and more criticism, and a great many new classifications are proposed. A number of researchers recognize a continuum of channel forms rather than discrete types, while others see abrupt transitions between straight, meandering and braided channels. Fluvial pattern transformation is becoming the leading edge and weak point of present sedimentology. In order to direct hydrocarbon exploration, based on reviewing the latest research progress in modern deposits, simulation experiment, outcrops and seismic study, the rule and controlling factors of fluvial pattern transformation were discussed, and some problems and corresponding countermeasures were proposed.The results demonstrate that the fluvial pattern transformation is mainly controlled by tectonic activities, sedimentary supply, climate condition and sea (lake) level change, and the former three factors are more important for ancient fluvial pattern transformation. Influenced by the above factors, from upstream to downstream one river usually changes from braided river to low sinuosity meandering river, high sinuosity meandering river and anastomosing river. However, the location of river is not the main factor to determine the transformation, as long as meeting the conditions, such as tectonic activities, provenance supply and climate abrupt change, and the fluvial pattern may transform. However, the petroleum geologists have not paid much attention to the researches of fluvial pattern transformation, which have not be used to interpret ancient fluvial deposits, and this will be a focus of future research directions.