The invention relates to the technical field of box carrying, and discloses a synchronous and automatic loading system for a whole stack of boxes. The synchronous and automatic loading system comprises a plurality of stand columns fixed to the ground, transverse beams are arranged between the upper ends of the stand columns, a longitudinal beam is arranged between the two transverse beams and is provided with a sliding base capable of sliding along the longitudinal beam, a lifting base is arranged on the sliding base, and a grabbing device is arranged at the lower end of the lifting base; a conveying belt is arranged at the position, at one ends of the transverse beams, of the ground, a push plate is arranged on one side of the tail end of the conveying belt, and a box positioning platform is arranged on the other side of the tail end of the conveying belt; and a plurality of parallel supporting strips are arranged on the top face of the box positioning platform, the top faces of the supporting strips are higher than the top face of the conveying belt and are lower than the top faces of trays on the conveying belt, a plurality of avoiding grooves are formed between the supporting strips, and insertion rods capable of extending into the avoiding grooves in a one-to-one correspondence manner are arranged at the lower end of the grabbing device. By means of the synchronous and automatic loading system, automatic carrying and automatic unloading of the whole stack of boxes can be achieved, the hand labor intensity is greatly reduced, and the carrying efficiency is improved.