Abstract: Controlled cooling is the key technology for hot strip after rolling and coiling temperature control is the hardcore of the cooling process. Based on the improvement of cooling system in a hut snip mill, the online offset and problems in the coiling temperature control before reform were discussed, including the cooling capacity was insufficient to thick strip, the uniformity of the temperature control along rolling direction was poor relatively, etc. The improving measures were suggested on the cooling equipment, the cooling strategy and also the online mathematic control model. Model parameters are optimized at the same time. Self-adaptive capacity of mathematic model is improved meantime. The experimental result shows that the new system after being optimized offers steady and reliable performance, and high precision.