This study thoroughly investigates the influences of n-type AlGaN cladding layers and upper waveguide layers (UWG) on the optical field distribution and electrical characteristics of GaN-based green laser diodes (LDs). It is found that the optical field leakage can be evidently suppressed by increasing the thickness of the AlGaN cladding layer or the indium content of the InGaN upper waveguide layer. Moreover, compared with LDs with In0.02Ga0.98N UWG, the LDs with a higher indium content of In0.05Ga0.95N UWG perform better because of the larger optical confinement factor. Therefore, coregulation of the n-type cladding layer and the UWG can improve the optical field distribution, enhancing the performance of GaN-based green LDs.