A relationship of residual stress distribution and surface molding states on polymeric materials is presented in thin-walled injection molding. The residual stress is computed by computational numerical analysis, observed with stress viewer and birefringence. The residual stress on polymeric parts can allude the surface quality as well as flow paths. The residual stress distribution on polymeric parts is related with thickness, gate layout, and polymer types. Molecular orientation on polymeric parts is also important in thin wall injection molding. The residual stress and molecular orientation are related to the surface molding states intimately. Analysis of the residual stress is validated through photo-elastic method and surface molding states..