The invention discloses a more reliable seat suspension mechanism, composed of a lower frame, a rigidity adjustment device and an upper frame, wherein the rigidity adjustment device is located between the lower frame and the upper frame; the rigidity adjustment device is composed of an inner support, an outer support, two springs, a damper and a rigidity adjustment assembly; the upper frame is composed of a front side frame, a rear side frame, a left side frame and a right side frame; the inner support and the outer support compose an interior shear-type mechanism; the rigidity adjustment assembly is composed of a pull rod, a lever, a body box and an adjustment screw; the lever is located in the body box, the adjustment screw penetrates through the body box and the lever, the lever is connected with the adjustment screw via a nut, and the fulcrum of the lever is hinged together with the body box, and the other end of the lever is hinged with a pull rod; one end of each of the two springs is hooked at two ends of the pull rod, and the other end of each of the two springs is hooked on a cross rod; the end part of the adjustment screw exposes out of the upper frame; and the damper is slantwise arranged between the lower frame and the upper frame. The more reliable seat suspension mechanism disclosed by the invention has a sufficient suspension amount and no sway phenomenon.