Various functions of polymer composites, including electrical conductive, thermo conductive, dielectric, EMI shielding, strain sensing, etc, has been extensively investigated. These functions need to be delivered by functional filler or structure. Therefore, the morphological control of these functional filler or structure should play vital role on the final properties of these functional polymer composites. Conductive polymer composites (CPCs) is used as an example. In recent years, CPCs containing large aspect ratio filler (CNT and graphene) has gained extensive attention. However, there are still two issues needs further investigation: 1. How to control the conductive network structure and their electrical property more effectively using morphological control methods as well as filler mobility; 2. How to design and fabricate special network structure for various functions. The author has carried out a series of studies focusing on “The relationship between different morphological control methods--filler network morphology & property—functionality”. Through combing different processing methods and take advantage of filler mobility, new processing methods as been developed to control filler network morphology, novel multi-functional CPCs have been designed and prepared. Herein, CPCs, strain sensing polymer composites and dielectric polymer nanocomposites will be used as examples to illustrate the effect of morphology control on these functionalities.