Abstract: Small animal PET/MRI is an integrated imaging device that combines the high-performance molecular imaging function of PET with the excellent soft tissue contrast function of MRI, offering unique advantages and significant application value in drug development and evaluation, pharmacology, and mechanistic studies of diseases. To verify the feasibility and accuracy of this device in quantitative analysis, this study evaluated the linear detection range, stability, and quantitative performance of the Bruker BioSpec 94/30 USR + PET insert for ¹⁸F. High-resolution MRI images were utilized to remove interference from factors such as the gallbladder and blood vessels, ensuring accurate in vivo quantification in animals. The results demonstrate that the Bruker BioSpec 94/30 USR + PET insert small animal PET/MRI system exhibits excellent linearity (R²=0.9992) within the activity range of 1-1500 μCi, good reproducibility, and accurate in vivo quantitative performance. This provides reliable data for subsequent studies utilizing the Bruker BioSpec 94/30 USR + PET insert for in vivo visualization, distribution, metabolism, and pharmacodynamic evaluation of nuclear tracers.