Against the backdrop of the green and low-carbon transformation and capacity upgrading of the cement industry, the retrofit of the kiln tail preheater is a key measure to improve energy efficiency and realize energy conservation and emission reduction, issues such as structural compatibility, load transmission and construction safety are of crucial importance. Based on engineering practice, aiming at the structural problems in the internal retrofit of the 5-stage preheater, this paper systematically sorts out typical renovation types including the heightening renovation of the precalciner inside the preheater tower, the addition of a new precalciner outside the tower (supported column scheme ), and the transformation of the 5-stage preheater into a 6-stage one, and deeply analyzes the structural characteristics, mechanical behavior and technical difficulties of various schemes. It summarizes the reinforcement technologies for key parts such as steel beams, steel columns, foundation, column base joints and the void defects of concrete-filled steel tube columns, and proposes a structural inspection and appraisal process with "investigation-detection-calculation-evaluation" as the core. Finally, it is pointed out that the structural reinforcement for more difficult renovations such as the upgrading from 5-stage to 7-stage preheater needs continuous breakthroughs in three aspects: load optimization, innovation of analysis methods and application of new reinforcement technologies, so as to provide technical support for similar projects in the industry.