Objective To study MRI features of fibroma of tendon sheath(FTS)and giant cell tumor of tendon sheath(GCTTS), so as to improve the diagnosis and differential diagnosis of two lesions. Methods Seventeen patients with FTS and 27 patients with GCTTS confirmed by operation and pathology were retrospectively analyzed. All patients were examined with MRI. The location, size, shape and the relationship with the surrounding tissue, the signal feature and enhancing pattern of the two groups were compared. Imaging features in the two groups were assessed and analyzed by using independent samples t test and Chi-square test. Results FTS were nodular or mass-like lesions(n=11). Few lesions appeared adjacent bone absorption(n=2). On T2WI, the lesions showed peripheral low signal ring(n=6)or internal mixed low-signal intensity of was striped or filamentous configurations(n=10). The volume of low-signal intensity accounted for more than 2/3 of the total lesion's volume(n=6). Enhanced T1WI, tumors revealed ring enhancement(n=6). GCTTS appeared mostly lobulated(n=16), common with adjacent bone compressive absorption(n=9). On T2WI, most of lesion had a peripheral low signal ring(n=22). Tumors revealed mixed high signals intensity with granular or patchy irregular low signal intensity scattered in the mass(n=17), the area of low signal accounts for less than 1/3 of total neoplastic volume(n=18). On contrast T1WI, GCTTS appeared heterogenous enhancement. Statistical analysis showed that the shape of the lesion, the presence or absence of compressive bone absorption, the presence of a low signal ring around the lesion, the shape of the Low-signal in T2WI and the proportion, and the presence of circumferential enhancement(P<0.01), there were statistically significant differences between the two. And there was no statistically significant difference in the age, gender and location of disease(P>0.05). Conclusion FTS and GCTTS has a different characteristic of MRI features. FTS were nodular or mass-like, T2WI signal was mixed low, the shape of the low-signal was striped or filamentous, accounting for more than 1/3 of total lesion's volume, enhanced T1WI, tumor shows ring enhancement;GCTTS appears mostly lobulated.Most of lesion has low signal ring, common with adjacent bone compress compressive absorption. T2WI, tumor reveals mixed high signals intensity with granular or patchy irregular low signal intensity scattered in the mass. The area of low signal accounts for less than 1/3 of total neoplastic volume.