Quasi-steady-state H-mode has been achieved by combination of two lower hybrid w aves in HT-6M tokamak.Plasma energy confinement time increases by two times,and the particle confinement time increases by a factor of three under a high plasma density condition.The wave diffusion and current radial diffusion code is used to simulate the experimental data on HT-6M.The calculated results show that the off-axis power deposition of lower hybrid wave is formed due to the low toroidal magnetic field and high plasma density.Reversed sheared(RS) configuration of th e plasma current density is formed during H-mode phase.The RS configuration and internal transport barrier are attributed to the enhanced confinement improvemen t.The experimental data also gives the evidence for the reversed shear formation .