The accuracy of the T1 measurement depends on the accuracy of the flip angle (FA). The FA is non-uniform in a slice across the slice-thickness direction, which can result in serious T1 measurement error. Although it has been recognized that measuring the FA regional inhomogeneity in a volume is important, the effect of the slice profile is still less known. In this work, the slice-profile effect is studied systematically for various common experimental conditions. The results provide essential guidelines for experiment design and scan parameter selection for the T1 measurement with steady-state magnetization (e.g., DESPOT).