In this dissertation, multi-wall carbon nanotubes (MWNTs) were synthesized by chemical vapor deposition (CVD), and incorporating carbon nanotubes, nano-alumina into epoxy and mortar, we synthesized nanocomposite: MWNTs/epoxy and nano-alumina/mortar. And their mechanical properties were studied by experiment. The carbon nanotubes and nanocomposite were also characterized with Transmission electron microscopy (TEM), Scanning electron microscopy (SEM) and electron dispersive spectra (EDS) etc. Enhancing mechanism of nano-materials also was discussed.According to experiments, the critical challenge of synthesis of nano-composite lied in uniformly dispersing nano-materials and synthesis of nano-materials. By using high speed mixer or ultrasonic wave mixer, nano-composite was successfully synthesized by direct admixture. Tensile, compressive strength of MWNTs/epoxy and early age compressive strength, elastic modular were greatly higher than test samples, respectively.We also utilized different composite theories to study tensile strength of MWNTs/epoxy and elastic modular of nano-alumina/mortar. The theoretical results of MWNTs/epoxy tensile strength were higher than experimental result for agglomeration result of MWNTs was not considered in these theories; we also studied elastic modular of nano-alumina/mortar with theory in which nano-alumina/mortar was seen as three-phase composite, the results showed that theoretical results were lower than experiment for effect of base reinforced was ignored in the theory. As complexity of nano-materials and nano-composites, it is difficult to exactly forecast their mechanical properties by present theory, and a great amount of effort must be made to improve the theory of composite. At the same time, further investigations must be made in enhancing mechanism of nano-materials.