The invention provides a long-edge edge trimming device for an edge trimming saw. The long-edge edge trimming device comprises a moving mechanism and saw benches, wherein the saw benches are symmetrically arranged on two opposite side edges of the moving mechanism; the moving mechanism drives a plate to pass the saw benches to finish edge sawing; the moving mechanism comprises a first bearing platform, a second bearing platform and a conveying mechanism for the plate; the second bearing platform moves forwards or backwards on the conveying mechanism and is located in the middle of the first bearing platform; the first bearing platform has a lifting function; a pressing plate mechanism is further arranged on the second bearing platform; each saw bench comprises a bench face and a rack which supports the bench face; a saw passing groove is formed in the bench face; a circular saw is located below the bench faces, and a part of the saw blade of the circular saw penetrates through the saw passing grooves from bottom to top and is exposed above the bench faces; and pressing plate devices are further fixed on the bench faces. Compared with the prior art, the moving mechanism and the saw benches are matched perfectly, so that during a moving process, the edges of the plate is sawn; and during an edge sawing process, the plate is stable and free from displacement and floating.