The physical design for a novel low-energy compact-storage-ring-based extreme ultraviolet (EUV) light source was systemically studied. The design process considers the linear and nonlinear beam optics, including transverse matching and the optimization of the dynamic aperture, momentum aperture, and beam lifetime. With a total circumference of 36.7 m and a beam energy of 400 MeV, the storage ring can operate with an average beam current of up to 1 A. With the undulator as the radiator, this facility has the potential to emit EUV radia-tion at 13.5 nm with an average power exceeding 10 W within the bandwidth. In addition, the collective instabili-ties of the lattice at high beam current were analyzed; it was found that the typical instabilities which may occur in an electron storage ring can be reasonably controlled in our design. With the advantages of variable beam energy and current, this design exhibits great promise as a new can-didate for various EUV lithographical applications requir-ing tunable radiation power.