The invention discloses an automatic rotary type beam transport flat car which comprises a traveling trolley (1), a chassis (2) and a tray (3). The chassis (2) is fixed on the traveling trolley (1), and a motor (7) is fixed on an inner side of the traveling trolley (1). The automatic rotary type beam transport flat car is characterized in that a rotary device (4) is fixedly arranged on the chassis (2), the tray (3) is positioned on the rotary device (4), and the chassis (2) and the tray (3) are movably connected through a central mandrel (10). The rotary device (4) consists of a roller assembly (9) and a jack (11), the roller assembly (9) is fixed on an upper end face of the chassis (2), and the jack (11) is fixed on a side face of a central beam (8) of the chassis (2). The automatic rotary type beam transport flat car has the advantages that the tray can automatically rotate and the automatic rotary type beam transport flat car is simple in structure.