<p>As an advanced additive manufacturing technology, laser cladding is widely used for preparing high-performance coatings and repairing critical components. However, the process involves complex thermo-mechanical interaction and needs to deal with several challenges, such as residual stress, local deformation and pores. Here, a multi-scale approach consisting of finite element (FE) method and molecular dynamics (MD) simulation combines with experiments to systematically investigate the laser cladding of titanium alloy material. At the macroscopic scale, the effects of laser power and scanning speed on temperature distribution, residual stress and deformation are analyzed by FE method. At the microscopic scale, MD simulation reveals the mechanisms of powder melting, pore formation and evolution of crystal structure. Good agreements between macroscopic morphologies by FE method and experiments, as well as microscopic porosities by MD simulation and experiments are achieved, respectively. Higher laser powers increase the size of melt pools and residual stress, while higher scanning speeds lead to incomplete melting and higher porosity. This work provides theoretical support for optimizing laser cladding parameters to achieve the balance between melt quality, stress distribution and microstructural evolution.</p>