InAs/GaAs quantum dots (QDs) with graded InxGa1-xAs strained-reducing layer (SRL) are grown by metal-organic chemical vapor deposition, the effects of Indium (In) composition and thickness in InxGa1-xAs on QD morphological characteristics and optical properties are investigated. Compared with InxGa1-xAs SRL with fixed In content, gradient InxGa1-xAs SRL can further improve the growth quality of InAs QDs, enhance luminescence intensity and extend emission spectrum toward longer wavelength. (C) 2010 Elsevier B.V. All rights reserved.