We develop a modified two-step method of growing high-density and narrow size-distribution InAs/GaAs quantum dots (QDs) by molecular beam epitaxy.In the first step,high-density small InAs QDs are formed by optimizing the continuous deposition amount.In the second step,deposition is carried out with a long growth interruption for every 0.1 InAs monolayer.Atomic force microscope images show that the high-density (～5.9x1010 cm-2) good size-uniformity InAs QDs are achieved.The strong intensity and narrow linewidth (27.7 meV) of the photoluminescence spectrum show that the QDs grown in this two-step method have a good optical quality.