For the strip flatness defects problem of strip steel caused by uneven plastic deformation in the transverse direction of strip steel, the mechanism for the strip flatness problem of strip steel during the cold tandem rolling process was studied. Considering the hereditary characteristics of strip steel between stands, a strip flatness prediction model suitable for UCMW (Universal Crown Mill with Work roll shifting) was established for the cold tandem rolling process, which realized the quantitative predictions of strip flatness at the exit of each stand in the cold tandem rolling mill and provided a theoretical basis for analyzing the factors influencing the strip flatness. The results show that the predicted strip flatness curves are consistent with the measured distribution trends, with the unit prediction errors within 2 I and the overall strip flatness errors within 4 I. This indicates that the model has high prediction accuracy and can meet the requirements for predicting the strip flatness condition in actual production and simulation analysis. The strip flatness defects of strip steel are controlled effectively by the accurate strip flatness prediction, which directly improves the flatness and surface quality of the product.