Quantitative susceptibility mapping (QSM) is a promising technique for measuring iron concentration in patients with liver iron overload. In liver QSM, the constraints of scan time in a breadth-hold and the requirement of a short first echo time lead to limited imaging resolution, with anisotropic voxels. In this work, we characterized bias in liver QSM with anisotropic imaging resolution in simulation, a 3D printed liver phantom and patients. Our study shows that resolution-induced bias is related to the downsampling direction and is spatially-varying. In vivo results suggest the liver imaging resolution along the left-right dimension may affect liver susceptibility measurements.