The present invention discloses an automatic scoring system for a beer pong game to implement an automatic scoring function of the beer pong game using a radio frequency identification (RFID) technology, comprising: a game table equipped with a RFID reader and a plurality of RFID antennas; a plurality of game cups with electronic tags being attached at bottoms thereof; at least one game ball with an electronic tag embedded therein, and a computer that processes data read by the reader from the electronic tags and controls a scoring procedure of the beer pong game, wherein the RFID antennas are placed at a plurality of predetermined positions in a game zone of the game table, the plurality of predetermined positions corresponding to possible positions of the game cups placed according to game rules. The present invention also discloses an online beer pong game system, comprising the automatic scoring system for a beer pong game as mentioned above, which online beer pong game obtains game data in real-time from a computer of the automatic scoring system using a cloud storage technology and a mobile phone application, such that competitors of the beer pong game can online participate in the game, track game scores and statistics, compare results with other competitors on a global scale.