The invention discloses an automatic steel pipe straightening machine applicable to steel pipes of multiple specifications. The automatic steel pipe straightening machine comprises a machine tool, a pipe conveying assembly, a straightening assembly and a collecting assembly. The straightening assembly comprises two inverted-U-shaped supports arranged on the machine tool. A master lower roller anda slave lower roller are correspondingly pivoted to the opening ends of the two supports. A driving motor for driving the master lower roller is arranged on the machine tool. The slave lower roller isin transmission connection with the master lower roller through a belt. The straightening assembly further comprises a sliding frame with two ends correspondingly and slidably inserted into the two supports. Two upper rollers are pivoted to the sliding frame. The pipe conveying assembly comprises a pipe conveying box arranged on the machine tool. A pipe groove is formed in the pipe conveying box.A pipe conveying opening opposite to an inlet is formed in the bottom of the pipe groove. A sliding hole and an electric sliding table are arranged at the bottom of the pipe groove. A sliding block of the electric sliding table slides in the sliding hole. The collecting assembly comprises a collecting groove and an inclined plate obliquely arranged on the collecting groove. By the adoption of theautomatic steel pipe straightening machine, most of labor is saved, the efficiency is higher, and the cost is low; and the automatic steel pipe straightening machine can be adjusted for the steel pipes with different pipe diameters, so that the steel pipes with different pipe diameters can be straightened.