In this chapter, property oriented surface engineering of CNTs for polymer composites is first reviewed by emphasizing the effect of interfacial interaction between CNTs and host polymers on a given property (e.g., mechanical, electrical and dielectric properties) of final composites. Then, an example of non-covalent modification of CNTs for dielectric polymer composites is presented in detail, showing how the surface engineering changed the interfacial interaction and thus favored the dielectric properties of the composites.