GaAS/GaAlAs heterostructure rib waveguide coupler with stepped [Triangle Open]β Schottky electrodes has been investigated by using ion-etching and lift-off mask techniques, and optimization design of device structure and lowering epitaxy layer carrier concentration. Total losses of 10dB and extinction ratio of 26.8dB were obtained for single-mode operation at 1.3μm. Operation principle of this device and its design considerations were described in detail. Structural parameters of the coupler were given. The testing method and results for the coupler were presented. The structure of this coupler is compatible with the manufacturing engineering of the devices such as semiconductor lasers, easier to be adopted in repetitive manufacturing.