Based　on　wavelength　beam　combining,　we　use　grating　diffraction　and　external　cavity　feedback　to　lock　all　elements　of　the　laser　diode　array(LDA)　in　different　wavelengths,　and　the　neighboring　emitters　have　slight　difference　in　locked　wavelength.　The　output　beam　from　the　external　cavity　coupler　mirror　is　nearly　parallel　with　the　same　beam　quality　as　single　element　of　the　LDA,　and　its　brightness　grows　with　the　element　number　of　the　LDA　increasing.　The　1　cm　linear　array　used　in　the　experiment　consists　of　19　wide-aperture　diodes　with　diode　width　of　100　μm　and　a　fill　factor　is　0.2.　When　the　free　operating　output　power　is　49.8　W　and　the　maximal　injection　current　is　60.6　A,　the　combined　beam　power　is　20.1　W,　the　wavelength　spread　is　about　15　nm,　and　the　far　field　divergence　angle　varys　from　70　mrad　in　free　operating　to　1.66　mrad　in　fast　and　slow　axes　in　a　single　cavity.　The　corresponding　beam　quality　factor　is　32,　which　is　the　same　as　that　of　single　element.