[en] In this work, the options, profile and beam loss of 3-GeV proton beams are studied for new facilities for the physics using short-live nuclide beams, the muon science and the neutron science established in the JAERI/KEK joint project for high-intensity proton accelerator. The beam optics and beam loss are calculated with the TRANSPORT and DECAY-TURTLE codes. The structure of the beam line is studied with the TRANSPORT code. A candidate beam line is obtained, which has 86 m in length and can be filled in the present configuration plan of the facility. Furthermore, the profile and spill of the beam are calculated with DECAY-TURTLE code. It is recognized that the spill of beam can be achieved to be smaller than 15 % as a goal of the beam line design and that beam can be delivered in uniformly shape in 13 cm width and 5 cm height, on the neutron target. (author)