This paper presents a design method for the low sensitivity optimal modal feedback control of a class of linear distributed-parameter systems with distributed control. The systems are described by differential operators which can be decomposed by a set of non-interacting first-order ordinary differential equations. Optimal control theory of lumped-parameter systems is then applied to construct the control late with modal feedback. Sensitivity of the optimal system is analysed. Modal state and control sensitivity functions are defined and low sensitivity modal feedback control law is constructed. The superiority of the low sensitivity modal feedback control system to the standard optimal control system is illustrated by a numerical example.