Two sets of new surface integral equations, based on the Stratton-Chu formulation, are developed to analyze the interactions of an incident electromagnetic wave with a 2D metallic nanostructure for the transverse-magnetic (TM) mode and the transverse-electric (TE) mode, respectively. For the former, the surface integral equations are in terms of the surface components of the tangential magnetic field H z , the normal displacement field D n , and the tangential electric field E t . As to the latter, the equations are in terms of the surface components of the tangential electric field E z , the normal magnetic flux density B n , and the tangential magnetic field H t . The numerical results show that for TM mode a standing wave pattern is observed on the backside of a metallic nanoscatterer with a size of several hundreds nanometers, which is caused by two surface plasmon waves creeping along the boundary clockwise and counterclockwise. However there is only a shadow zone on the backside of the metallic scatterer for TE mode.