YBCO tapes are subjected to various stresses such as tension, compression, bending, twisting and fatigue in practical application. The influence of mechanical fatigue on the critical current decay behavior has been studied by several research teams. The impact of background magnetic field on the critical current degradation under tensile fatigue loading, however, has been rarely investigated. In this work, strain controlled fatigue behavior including strains up to 0.746% and strain ratios of 0.3, 0.5 and 0.7 will be studied. In addition, the effect of mechanical fatigue strain on critical current under background magnetic field was evaluated at different field angles and fields.