Modern nanotechnology takes advantage of various nanomaterial properties, such as optics, thermo-plasmonics, mechano-plasmonics, magneto-plasmonics, etc., where one property is enhanced or modified due to another. Thus, nanoparticle aggregation and fragmentation, formation of bi-metallic, alloy, Janus, and/or multi-component nanoparticles pave the way toward practically unlimited modification possibilities of their absorption spectra, but also of their properties and potential functions in various fields including medicine, solar energy, catalysis, etc. Among promising methods of nanoparticle synthesis, lasers-based methods are widely used for nanoparticle formation in liquids and in solid matrices, but also for 3D laser manufacturing, nanoparticle-assisted surface, and material analysis, cancer theranostics, etc. Laser-induced nanoparticle sintering and fragmentation are particularly efficient for tailoring the properties of nano-objects and, in particular, for nanoalloy formation and numerous multi-material nano-complexes. This becomes possible due to the absence of thermodynamic equilibrium during the extremely fast laser heating process. Such laser interactions involve a set of electronic and ionic processes, various phase transitions, diffusion, mixing, aggregation, fragmentation, chemical reactions, etc. In this talk, attention will be particularly focused on multi-physical and multi-scale simulations of such processes as laser ablation, laser treatment of nanocomposite materials, size-dependent nanoparticle absorption and local field enhancement, photo-induced free carrier generation, and heat transfer. The properties of the obtained nanomaterials will be analyzed and compared with the available experiments. Additionally, recent results of all-atomistic molecular dynamics simulations performed for binary and multi-material nanoparticles will be presented. The role of laser parameters, nanoparticle material properties, sizes, and composition will be analyzed.