Abstract: A controller design is proposed based on spectral decomposition of operator semigroup for linear neutral delay systems (NDSs). When the norm of the neutral term is less than one, by spectral theory and projection operator, the infinite dimensional solution space of system is decomposed into the direct sum of finite dimensional unstable generalized eigensubspace and infinite dimensional stable subspace. Then for the finite dimensional subsystem, the control law of state feedback is obtained. And the asymptotic stability of the colsed loop system with state feedback control is proved by the projection operator. Finally, a numerical example demonstrates the effectiveness of the proposed approach.