We have grown the InGaAsSb/AlGaAsSb quantum well laser structure on a GaSb substrate using solid-state source molecular beam epitaxy and successfully fabricated GaSb-bas ed laser diode operated at 2.0μm. The dependence of threshold current density on the cavity length was studied at room temperature in continuous-wave mode.It is found that the threshold current density is 135A/c m^2when the device has infinite cavity length.The internal quantum efficiency is measured as 61.1% and int ernal loss is 8.3cm－1,while the device is operating in the continuous wave mode at room temperature.The out pow er slope efficiency is 112mW/A and the maximum output optical power is 72mW.High device performances are obtained from the characterization data of the laser diodes.In addition,the tuning characteris tics of the lasing wavelength are studied by varying the cavity length and the i njection current of laser diodes.The operating wavelength shifts to longer direction with a rate of 0.475nm/mA with the increase of injection curre nt.The device with longer cavity length operates in longer wavelength.The laser wavelength depends monotonously on the cavity length.The above dependence is typical for GaSb based quantum well laser diodes in our studies.