The invention relates to a beam test support seat which comprises a base plate, wherein a lower roller support seat is fixedly arranged on the upper surface of the base plate; a lower roller is put on the roller support seat; lower support springs are symmetrically arranged at two sides of the lower roller; a lower support plate is arranged on the upper surface of each lower support spring; U-shaped support plates are welded on the base plate at two sides of the lower roller support seat; each U-shaped support plate is provided with one horizontal adjusting screw; upright posts are welded at the upper ends of the two U-shaped support plates; a locking nut is arranged on the upper end part of each upright post; one cover plate is fixedly arranged at the upper end of each upright post; an adjustable test beam placement space is enclosed by the cover plates and the U-shaped support plates; an upper roller support seat is welded on the lower end surface of each cover plate; two upper pressure springs are arranged on the lower surface of the upper roller support seat; and the lower ends of the upper pressure springs are connected with upper support plates. A good constraint can be provided for the beam end in the test process, and meanwhile, displacement of the beam support seat in the horizontal or vertical direction can be limited, so that great influence of overlarge displacement on the test result is avoided.