Abstract: The Silurian and Devonian periods were critical ages for the development and evolution of the Kalamaili collision belt. By studying the Silurian and Devonian sedimentation in the southern margin of Kalamaili collision belt, it is concluded that the Baishanbao Formation in Silurian period should belong to infralittoral sediment called storm surge rather than sediment of beach or shallow sea. The gravity flow turbidite sequences and gravity flow drainage channel deposit discovered in the lower segment of the Kalamaili Formation indicate a sedimentary environment of slope to bathyal facies rather than littoral facies. Continental molasse discovered in the late Devonian Keankuduke Formation represents the sedimentary of continent-continent collisional orogeny, which records the formation, evolution and orogenic process of the basin. The result in this study not only enriches the research content of tectonic evolution in the Kalamaili collision belt, but confirms that oceanic crust subduction and continent-continent collision happened in late Devonian