Long-wavelength GaN based light-emitting diodes are of importance in full color displays, monolithic white light-emitting diodes and solid-state lighting, etc. However, their epitaxiM growth faces great challenges because high indium (In) compositions of InGaN are difficult to grow. In order to enhance In incorporation and lengthen the emission wavelength of a InGaN/GaN multi-quantum well (MQW), we insert an InGaN underlying layer undeeath the MQW. InGaN/GaN MQWs with various InGaN underlying layers, such as graded InyGa1-yN material with linearly increasing In content, or InyGa1-yN with fixed In content but different thicknesses, axe grown by metal-organic chemical vapor deposition. Experimental results demonstrate the enhancement of In incorporation and the emission wavelength redshift by the insertion of an InGaN underlying layer.