asymptotically cylindrical flows are ancient solutions to the mean curvature flow whose tangent flow at $-\infty$ are shrinking cylinders. in this talk, we study quantized behavior of asymptotically cylindrical flows. we show that the cylindrical profile function u of these flows have the asymptotics $u(y,\omega, \tau) = \frac{y^{t}qy - 2tr q}{|\tau|} + o(|\tau|^{-1})$ as $\tau\rightarrow -\infty$, where $q$ is a constant symmetric $k\times k$ matrix whose eigenvalues are quantized to be either 0 or $-\frac{\sqrt{2(n-k)}}{4}$. assuming non-collapsing, we can further draw two applications. in the zero rank case, we obtain the full classification. in the full rank case, we obtain the $so(n-k+1)$ symmetry of the solution. this is joint work with wenkui du.