Abstract. A high confinement plasma by using LHCD has been obtained on HT-7 superconducting Tokamak. An obvious internal transport barrier has been observed. Energy confinement time increases from 14.6 ms (OH phase) to 24.5 ms (LHCD phase). The H confinement factor reaches to 1.42(LHCD phase). The experimental results are in good agreements with the simulations of ray tracing code and 2-dimensional Fokker-Planck equation. The edge plasma characteristics around the last closed flux surface were investigated by Langmuir probes. The results indicate that turbulence and transport are suppressed greatly by lower hybrid wave. Studies show that the high confinement plasma is mainly ascribed to a sheared flow resulted from the varied radial electric field.