A quasi-zero stiffness composite beam structure for controlling low-frequency vibration of a longitudinal axial flow threshing drum. The structure comprises a left column (2), a right column (3), a quasi-zero stiffness composite beam (5), a composite beam right connecting member (8), and a composite beam left connecting member (9). A right side of the quasi-zero stiffness composite beam (5) is connected to the composite beam right connecting member (8). A left side of the composite beam (5) is connected to the composite beam left connecting member (9). The composite beam right connecting member (8) is connected to the right column (3). The composite beam left connecting member (9) is connected to the left column (2). The composite beam right connecting member (8) and the composite beam left connecting member (9) are connected, at a quasi-zero stiffness composite beam bearing position, to a threshing drum shaft (603) via a threshing drum bearing seat (602). When the combined total stiffness of the positive stiffness of a positive stiffness cross beam bearing a dynamic load of a longitudinal axial flow threshing drum and located in a balance position and the negative stiffness generated by prestress at an end of a negative stiffness bending beam shaft is approximately zero, a quasi-zero stiffness composite beam balance point is formed. The positive and negative stiffness beam structures are fixed, in a position where the quasi-zero stiffness composite beam is balanced, by a connecting screw. A gap between balance positions of the positive stiffness beam and the negative stiffness bending beam is filled with a connection pad. The invention can effectively control low-frequency vibration caused during longitudinal axial flow threshing.La présente invention porte sur une structure de poutre composite à rigidité quasi nulle pour commander une vibration basse fréquence dun tambour de battage à écoulement axial longitudinal. La structure comprend une colonne gauche (2), une
