Abstract：Based on previous researches in China and abroad, this paper expounds the depositional environment of Lower-Middle Silurian strata in Chaohu area in the aspects of lithology, sedimentary structure, fossil organism, formation cycle and geotectonics. According to the counterevidence and abundant new evidence, the authors have come to a conclusion different from previous researchers’ understanding: the Lower-Middle Silurian strata in the northern Chaohu area belong to the tide-dominated continental shelf instead of to the contour current deposit held by some previous researchers. This conclusion will contribute to the correct understanding of the Silurian geotectonic background and tectonic sedimentary evolution of this area.