Ignition characteristics in the D-T high field helical reactor of R=20 m, ā =2 m are analyzed by the “operation path method” on the P̄htτE2-T plane and “POPCON”. Based on the LHD scaling law, the strong magnetic field B0=12~15 T makes a reactor operable with a low confinement enhancement, leading to the low helium ash accumulation. POPCON analyses with the synchrotron radiation losses, the density limit and confinement time saturation effect show that merginal confinement factors to have the fusion power of 3 GW are 0.9 to 1.3 for Bo=15 T, and 1.1 to 1.6 for 12 T, respectively.