The complicated behaviors of InAs/GaAs quantum dots with increasing V/III ratio associated with several competing mechanisms have been described. The results demonstrate that the densities of InAs quantum dots can be tuned in a wide range from 105 to 1010 cm-2 by simply manipulating V/III ratio via metal-organic chemical vapor deposition. These results are mainly ascribed to the changes of coverage and In adatom migration length due to the increasing V/III ratio.