We report on the molecular beam epitaxial growth of self assembled GaSb quantum dots (QDs) on (0 0 1) GaAs substrates with an insertion layer. The insertion layer, which is a 4-monolayers (MLs) InxGa1-xAs (x=0.00, 0.07, 0.15, 0.20 and 0.25), is grown prior to the QD growth. With this InGaAs insertion layer, the obtained QD density decreases substantially, while the QD height and diameter increase as compared with typical GaSb QDs grown on conventional (0 0 1) GaAs surface under the same growth condition. The GaSb QDs on GaAs have the dome shape with elliptical base and the elongation direction of the base is along the [1 1 0] direction. When the InGaAs insertion layer is introduced, the distinct elongation disappears and the QD sidevvall shows facet related surfaces with (0 0 1) plateau on top. (C). 2015 Elsevier B.V. All rights reserved.