The dependence of resistance on temperature was measured for a Tl (2223) Ag-sheathed tape with high Ｊc(Ｊc＝１．５×１０４Ａ·ｃｍ-2，７７Ｋ，０Ｔ) in an applied magnetic field range from 0 to 0.8T. The experimental results were explained in terms of the thermally activated flux creep model. The relationship between activation energy U0 and the applied magnetic field H oriented parallel to and perpendicular to the ab plane is respectively Ｕ0∥＝０．２１ H-0.3(eV) and Ｕ0⊥＝０．１5 H-0.4(eV). The unit of H is in 0.1T. The dissipation independent of a macroscopic Lorentz force for H and measuring current I lying in the same ab plane and H parallel to I was discussed.