Spectral beam combining of a broad area diode laser is a promising technique for direct diode laser applications. Grating external cavity spectral beam combination bases on wavelength selection characteristics of the grating and external cavity diode laser technology to achieve the lock of the single emitter spectrum and the combination of all the sub beam combining elements into one output. The beam quality of the output is equivalent to a single beam combining element, and the brightness and power are greatly improved, simultaneously. Based on the coupler free grating external cavity structure, spectral beam combination of a single diode laser short array stripe was realized. The characteristics of spectrum, power and beam quality of the output beam were analyzed. At the pump current of 70 A, a continuous output power of 40.8 W was obtained. The fast and slow axis beam quality were 0.41 mm·mrad and 9.16 mm·mrad(including 95% energy) respectively, the corresponding electro-optic conversion efficiency was 38.4% and the brightness was up to 67.90 MW/(cm2·sr).