The invention discloses an automatic pipe distribution assembling machine of a radiator core. The automatic pipe distribution assembling machine comprises a machine frame, a pipe bank mechanism and pipe distribution mechanisms; the pipe bank mechanism is arranged on a cross beam which is installed on the machine frame and pushed by a cross beam air cylinder to do front-and-back movement; the pipe bank mechanism comprises a pipe bank fixing plate and a pipe groove, and the pipe bank fixing plate is arranged on the cross beam and further provided with a pipe hitting guide sliding rail and a pipe hitting guide sliding block; one end of the pipe hitting guide sliding block is connected with a pipe hitting head, and the other end of the pipe hitting guide sliding block is connected with a pipe hitting servo motor fixed to the pipe bank fixing plate through a crankshaft connecting rod; and the two pipe distribution mechanisms are symmetrically arranged on the left side and the right side of the right lower portion of the pipe bank mechanism. The automatic pipe distribution assembling machine is simple and reasonable, fixed-distance arrangement of radiating tubes is completed by the pipe distribution mechanisms in advance at back of an assembling platform, the fixed-distance arrangement process of the radiating tubes on the pipe distribution mechanisms and the remaining assembling processes can be carried out at the same time, the assembling efficiency is greatly improved, and the assembling time of the single radiator core is shortened.