The invention discloses a rolling stability checking method for a secondary cold rolling unit on the condition of small deformation. On the basis of laboratory rolling mill experiment and deformationtechnology research, by combining stable rolling factor analysis research results and the related optimization technology, for representative-specification steel species needing small-deformation rolling, the smallest stable rolling deformation is used as a target function, the restraint conditions are that slip and Jumping phenomena are avoided, and the secondary cold rolling unit small deformation stably rolling capacity is checked. On the premise of ensuring that slip factors and rolling stress are within the allowable range, the smallest value of reduction rate allele is obtained through optimization.