A highbrightness fibercoupled diode laser system is designed, based on the principle of astigmatism and ideal light source imaging theory. As an example, details of the calculation methods and design steps of the fiber coupled laser diode are given whose wavelength is 808 nm and output power is 10 W. Semiconductor laser beam can be coupled into the 50 μm core diameter optical fiber with a numerical aperture of 0.22. It is found that this fibercoupled system has an output power of 9.712 W, a coupling efficiency of 97.12% and a power density of 1.1224×106 W/cm2. The proposed method is simple in principle, and the designed fibercoupled system has high coupling efficiency, small size and strong practical value.