Architecture is the precipitation of history, not only the embodiment of technical level but also the inheritance of history and culture. Excellent architecture contains high historical value and emotional factors, and it continues to deepen over time. Nanotechnology is a new technology that was born in the late 1980s and is emerging. It mainly refers to the study of the laws of motion and interactions of electrons, atoms, and molecules in the composition system of matter in the range of 0.1 to 100 nm. Nanomaterials have special properties and structures, and the composite materials made of them have the effect of strengthening and toughening the polymer by virtue of their high-quality strength and toughness. Therefore, the aim of this text is to explore the application of nanocomposite building materials in modern architectural design and analyze the advantages and development trends of new building materials. The method in this paper is to use the method of experimental comparison to analyze the performance improvement effect of nanocomposite building materials on the current main building materials of concrete. By establishing a model to study the impact on the shrinkage and mechanical properties of cement-based materials, it can also improve the environmental performance and comprehensive evaluation of building materials. Corresponding conclusions are drawn through data comparison. When the amount of nanocomposite building materials is 1.5%, the chemical shrinkage value of the cement paste will increase by 58.2%, and the shrinkage strain will increase by 15.3%. When the fly ash content is 20%, the chemical shrinkage value of cement paste is reduced by 30.5%, and the shrinkage strain of concrete is reduced by 8.8%. Therefore, adding nanocomposite building materials to cement-based materials can promote cement hydration, optimize pore structure, and to a certain extent can make up for the shortcomings of mineral admixtures and achieve better improvement effects.