In this study,we focus on the controllability of fractional-order damped systems in linear and nonlinear cases with multiple time-varying delays in control.For the linear system based on the Mittag-Leffler matrix function,we defi ne a controllability Gramian matrix,which is useful in judging whether the system is controllable or not.Furthermore,in two special cases,we present serval equivalent controllable conditions which are easy to verify.For the nonlinear system,under the controllability of its corresponding linear system,we obtain a sufficient condition on the nonlinear term to ensure that the system is controllable.Finally,two examples are given to illustrate the theory.