Abstract: In this paper the basic concept and algorithm of eigenstructure assignment are extended. In respect of the assigning freedoms of eigenstructure a general conclusion is drawn as follows; for a completely controllable linear time-invariant system, r assigning freedoms of every closed-loop eigenvector or generalized eigenvector are offered by state feedback beyond specification of the set of closed-loop eigenvalues. Succeeding the algorithm assigning the eigenstructure with real distinct eigenvalues described in [3] and [4], two new algorithms are given to assign the eigenstructure with multiple eigenvalues or/and with complex conjugate eignevalues. These algorithms reveal the assigning freedoms of closed-loop eigenvectors or generalized eigenvectors and enable us to assign different classes of eigenstructure with an unified formula so as to avoid the complex number operations and simplify the numerical processing. A numerical example of an aircraft flight control system is presented to illustrate the application of eigenstructure assignment to designing a flight control system, and the diagrams of hybrid simulation based on the results of the above example are also given.The method of eigenstructure assignment in the modern control theory manifests some advantages and potentialities in dealing with the problems related to the analysis and design of multivariable linear time-invariant systems. This method may be developed into a new powerful means of designing multivariable linear system in engineering.