The invention discloses a single-overflow load-limit double-step hydraulic damper which comprises a hydraulic oil cylinder, a first piston rod, a second piston rod, a piston, a left end cover, a right end cover and an oil tank, wherein the hydraulic oil cylinder is externally provided with a valve block, and a first check valve, a second check valve, a third check valve, a fourth check valve, an overflow valve and the oil tank are arranged on the valve block; the inlet of the first check valve is communicated with a first working cavity of the hydraulic oil cylinder, and the outlet of the first check valve is communicated with the inlet of the overflow valve; the outlet of the second check valve is communicated with the first working cavity of the hydraulic oil cylinder, and the inlet of the second check valve is respectively communicated with the outlet of the overflow valve and the oil tank; the inlet of the third check valve is communicated with a second working cavity of the hydraulic oil cylinder, and the outlet of the third check valve is communicated with the inlet of the overflow valve; the outlet of the fourth check valve is communicated with the second working cavity of the hydraulic oil cylinder, and the inlet of the fourth check valve is respectively communicated with the outlet of the overflow valve and the oil tank; and the valve element of the overflow valve is provided with a damping hole. In the invention, damping energy dissipation is adopted under a low load and overflow load-limit energy dissipation and the damping energy dissipation are adopted under ahigh load so as to be convenient for processing.