In free-breathing radial k-space sampling with KWIC reconstruction, soft gating method can be adopted to reduce motion artifacts. We investigated optimal soft gating parameters for free-breathing hepatobiliary phase MRI. A programmable respiratory motion phantom with varying motion distance of 10, 20, 30 mm was imaged using six values of soft gating factor (SGF). Image contrast and sharpness were analyzed by calculating contrast ratio (CR) and full width at half maximum (FWHM). The CR and FWHM were not inferior compared with the reference standard images in any of the motion distances when the SGF was set at more than 1.4.