The threshold condition of a GaInAsP/InP surface emitting laser (λg=1.3 µm) has been discussed. It has made clear that the short cavity structure made of only epitaxial layers, the thicker active layer and high reflectivity mirror could improve the laser characteristics. By taking these points into consideration we have fabricated a surface-emitting GaInAsP/InP injection laser with short cavity length (∼10 µm) which operates at 1.22 µm of wavelength with threshold current of 160 mA (33 kA/cm2) at 77 K. The discussion was made also on the threshold current density by comparing the experimental and theoretical result.