The invention discloses an automatic butt joint charging system and an automatic butt joint charging method for a robot. The automatic butt joint charging system for the robot comprises a robot and a charging pile, wherein the robot comprises a robot shell, a robot positive electrode contact copper plate, an insulated sleeve, a robot negative electrode contact copper plate, two receiving infrared sensors and a robot control end; the charging pile comprises a charging pile shell, a charging pile positive electrode contact copper plate, a charging insulated sleeve, a charging pile negative electrode contact copper plate, a guide sleeve, (2n+1) transmitting infrared sensors, a baffle, a limiting switch, a charging adapter and a charging pile control terminal. Through detesting the strength of infrared signals received by the receiving infrared sensors at different positions on the robot, automatic butt joint between the robot and the charging pile is realized, and compared with the existing mode in which the charging pile adopts a manual aerial plug for charging, manual operation is reduced, and automatic charging on the robot by the charging pile is realized.