Considering a class of quasi-periodic excited piecewise nonlinear rolling mill system, a wealth of singular and nonchaotic dynamic phenomena are discovered. In this system, we mainly study generation mechanism of strange nonchaotic attractors and verification of the singularity of attractors. It is found through numerical methods that three routes can evolve into strange nonchaotic attractors, namely fractal route, intermittency route and Heagy-Hammel route. The largest Lyapunov exponent is used to verify its nonchaotic characteristics, and its strange property is verified by a rational number approximation to irrational number and phase sensitivity function.