The invention discloses a one-time punching device for a circular arc-shaped notch in a thin-walled pipe end. A female die sleeve is fixed to a base panel. A detachable female die is fixed inside the female die sleeve. A male die sleeve capable of moving bilaterally in the transverse direction is arranged on the base panel. A detachable male die with the initial position coaxial with that of the female die is fixed inside the male die sleeve and acts bilaterally in the radial direction of the female die. Punching cutting edges are arranged symmetrically on the two sides of the front end of the male die. A thin-walled pipe positioning hole is formed in the female die. Cutting edge sliding grooves corresponding to the punching cutting edges are transversely formed in the front end of the female die. Female die cutting edge holes communicating with the thin-walled pipe positioning hole coaxially and matched with the punching cutting edges are formed in the middles of the cutting edge sliding grooves. The circular arc-shaped notch is manufactured by only clamping a tubular product once, and the concentricity of the notch is guaranteed. A hydraulic system is adopted as a power system for driving and control, the travel can be adjusted and controlled by organically combining all electrical elements into a circuit, the operability is high, the female die and the male die can be rapidly replaced, and the one-time punching device is suitable for punching tubular products with different diameters.