As a special grade high-quality steel, 16Cr3NiWMoVNbE is the representative of the material of transmission components such as gear and shaft of aeroengine. At present, 16Cr3NiWMoVNbE steel is faced with the problems of large thermal deformation, long process cycle and poor matching of strength and toughness after carburizing strengthening. Laser phase transformation strengthening technology has the advantages of high processing efficiency, small thermal deformation and high surface quality, which can significantly improve the surface performance of the workpiece. However, this technology is often suitable for medium and high carbon steel. Therefore, the work aims to further increase the depth of the strengthened layer, refine the grain size, improve the mechanical property of surface, reduce the thermal deformation of the workpiece and shorten the process circle. The carburizing was combined with laser phase transformation strengthening. The "short-time" carburizing was used to improve the surface carbon content, and then the laser local rapid heating was used to provide an ideal channel for carbon atom diffusion. The microstructure evolution and strengthening-toughening mechanism of 16Cr3NiWMoVNbE steel strengthened by carburizing and laser phase transformation were revealed, providing new ideas and theoretical support for surface strengthening of key transmission parts of aero-engine.