This paper presents a waveguide model and a detailed calculation method for quantum well lasers with GRIN SCH structure,and analyzes how the aluminum density in Al xGa 1-x AsGRIN layer and the thickness of GRIN layer effect the effective refractive index.The optimum scale of the thickness of GRIN layer is given.We obtained the three dimension patterns of the near field profile for the abroad contact InGaAs/AlGaAs GRIN SCH quantum well lasers and the far field profile can be obtained from the near field profile by quick Foria transformation.We found the near or far field profile by calculation matched the result from measuring the actual devices.