Nanomaterials have permeated every sphere of life, industry, and research. Due to the unique piezoelectric properties of nanometer materials and piezoelectric types, it is possible to convert mechanical energy into electricity by certain mathematical relationships, equivalent to the energy supply for equipment. This capability allows for the creation of sensitive sensor elements that can perceive the external environment on various levels, including thermal, mechanical, electrical, and optical. The generation of piezoelectric nanogenerators indicates that nanomaterials devices can be expected to achieve a natural self-powered system without external power or only provide a small amount of energy, and play an irreplaceable role in the fields of microelectronics, artificial intelligence, and human-computer interaction. In this review, examples of nano-piezoelectric ceramic materials and nano-piezoelectric polymers that can be applied to flexible self-powered systems are listed, and the advantages and problems of these two kinds of materials in flexible self-powered systems are comprehensively analyzed. This paper focuses on the performance improvement of 0-3 nano-composites on the original piezoelectric ceramics and polymer materials and their application in the flexible wearable self-powered system. In addition, it summarizes the difficulties and challenges in their practical applications and provides future research directions for researchers.