An on-chip integrated semiconductor laser structure and a method for preparing the same. The structure includes: an epitaxial structure including a first N contact layer, a first N confinement layer, a first active region, a first P confinement layer, a first P contact layer, an isolation layer, a second N contact layer, a second N confinement layer, a second active region, a second P confinement layer, and a second P contact layer sequentially deposited on a substrate; a first waveguide and a second waveguide; a first optical grating and a second optical grating; and current injection windows.