Abstract: Objective To investigate the imaging effect of 0.5T low-field MRI on mice harboring primary liver tumors and subcutaneously transplanted tumors. Methods The 0.5T low-field MRI was conducted on mice bearing HepG2, S180, and liver tumor tissues of H-ras12V transgenic mice and primary liver tumors(Hras12V transgenic mice). The primary liver tumors of H-ras12V transgenic mice were confirmed by histopathological examination. Results The subcutaneously transplanted tumors (HepG2, S180, liver tumor tissues of H-ras12V transgenic mice) grew well and the tumor masses could be clearly observed by naked eyes and X optical detection. The MRI imaging results showed that the location of transplanted tumors clearly presented hypointense signal on T1WI and hyperintense signal on T2WI. The MRI imaging manifestations of three kinds of subcutaneously transplantated tumors were consistent. For the H-ras12V transgenic mice, the MRI imaging results showed that several separated regions presented hypointense signal on T1WI and hyperintense signal on T2WI in the location of liver. These regions were finally confirmed to be multiple liver tumors by anatomy and histopathological examination. Conclusion The low-field MRI provides an effective and noninvasive diagnostic method for detecting primary liver tumor and transplanted tumor in mice.