The invention relates to the correlation technical field of machining, in particular to a machining automatic conveying device. The machining automatic conveying device comprises a containing cavity.The containing cavity is fixed to a base through a support, a buffer cavity is formed in one side of the lower end of the containing cavity, an upper rack plate and a lower rack plate are arranged atthe upper end and the lower end of the buffer cavity, the motion directions of the upper rack plate and the lower rack plate are opposite, a conveying chain assembly mounted on the support is arrangedbelow the containing cavity, and multiple arc-shaped jaws are mounted on the conveying chain assembly at equal intervals. The design is novel, when the arranged arc-shaped jaws move to the upper endof the conveying chain assembly, the arc-shaped jaws abut against a drive plate fixed to the lower rack plate, when the arc-shaped jaws continuously move, the drive plate drives the lower rack plate to be opened, a columnar part falls into the arc-shaped jaws, under the blocking effect of the upper rack plate, the other columnar parts are prevented from falling out, thus, continuous automatic feeding is achieved, and the automation degree is high.