A method for fabricating a selective area metal bonding Si-based laser, optically or electrically pumped includes: forming a Si waveguide area and a bonding area in a Silicon-On-Insulator (SOI) wafer, and forming an isolating structure to separate the Si waveguide area from the bonding area; forming a metal multilayer for bonding, which also acts as ohmic contact layer in the laser when the laser is electrically pumped. A compound semiconductor optical gain structure is prepared by epitaxial growth and etched off the substrate. The compound semiconductor optical gain structure is aligned with the Si waveguide area in the SOI wafer and the compound semiconductor optical gain structure is bonded on the SOI wafer. The selective area metal bonding Si-based laser can be used as a light source in optoelectronic integration and Si photonics. The method may provide simple operation, flexibility, low cost, and low requirement for cleanness of manufacturing environments.