Abstract: From 1980-1984 some new results on multivariable linear system had been obtained by Chinese authors. The author of this paper gave out in 5 section the concept of (A, B)-characteristic subspace and its applications, the minimal polynomial matrix and its properties and the equivalence between state-space model and polynomial matrix and other corresponding results, some applications of Yokoyama canonical form especially in solving the disturbance decoupling problem, the properties of external skew prime polynomial matrices and their applications to output regulation, the internal model principle in frequence domain and robust control, and finally some other results were introduced.