本文通过斜管沿程沉淀效率试验，说明斜管的整个长度均起着固液分离作用，斜管起端不存在“过渡段”，通过斜管内流态试验说明，斜管起端的水流流态仍属层流，不存在“由紊流变层流”的过渡段。因而提出了斜管长度等于固液分离段长度即可，不必另加过渡段长度的新观点。 In this paper, the sedimentation efficiency test along the inclined pipe shows that the entire length of the inclined pipe plays the role of solid-liquid separation. There is no “transition section” at the beginning of the inclined pipe. Flow state test in the inclined pipe shows that the flow state of the flow at the beginning of the inclined pipe. Still laminar, there is no transition from turbulent to laminar flow. Therefore, it is proposed that the length of the inclined tube is equal to the length of the solid-liquid separation section, and there is no need to add a new viewpoint of the length of the transition section.