Objective To investigate the damage of retinal ganglion cell (RGC) axons in retinitis pigmentosa (RP) quantitatively by using reduced-filed-of-view DTI (rfov-DTI) together with optical coherence tomography(OCT).Methods Thirty four patients(68 eyes,Patient group)and 33 healthy controls (66 eyes, Control group) were enrolled in this study. Measures of rfov-DTI and OCT of both eyes in all subjects were performed by 3.0 MRI. The difference of fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (λ//) and radial diffusivity (λ⊥) were compared by two independent sample t test. The peripapillary retinal nerve fiber layer (RNFL) thickness in temporal and lateral nose, which data don't conform to normal distribution, were calculated by average and four quadrants and compared by Mann-Whitney U test,the average RNFL thickness and RNFL thickness in low quadrant and upper quadrant were compared by two independent sample t test.Spearman rank were performed to determine the correlation between DTI parameters of optic nerves (ONs) and RNFL thickness. Results The value of FA, MD, λ//, λ⊥, average, temporalside, nasal side, low quadrant and upper quadrant RNFL thickness in patient group were 0.445±0.078,(1.330±0.236)×10-3mm2/s,(5.502±0.263)×10-3mm2/s,(4.494±0.238)×10-3mm2/s,(104.7± 25.4)μm,(104.0±31.0)μm,(65.0±25.0)μm,(122.0±33.3)μm,and(117.4±37.7)μm respectively and the data in control group were 0.581±0.043,(1.079±0.146)×10-3mm2/s,(5.349±0.214)×10-3mm2/s,(4.195±0.126)× 10-3mm2/s, (101.2 ± 10.6)μm, (70.0 ± 10.8)μm, (81.3 ± 13.4)μm, (127.3 ± 12.5)μm, (126.3 ± 11.5)μm respectively.Compared with the control group,the value of MD,λ//,λ⊥were significantly higher but FA was significantly lower (t=-12.388, 7.394, 3.695, 9.062;all P<0.01). The temporal RNFL was significantly thicker while the nasal RNFL was much thinner than that in control group respectively(Z=-8.384,-4.518;all P<0.01);the average, low quadrant and upper quadrant RNFL thickness showed no significant differences compared with the control group(t=-1.217,-1.843, 1.049;P=0.227, 0.069, 0.297).Especially,there was a weak correlation between the temporal RNFL thickness and FA(r=0.268,P=0.029),however,no correlation of nasal RNFL thickness with mean FA was found(r=0.164,P=0.186). Conclusions rFOV-DTI together with OCT can provide information about the pathology of RGC axon disease in patients with RP.there is a weak correlation between the retinal nerve fiber layer and the pathological changes of optic nerve in the retinal ganglion cells,but the performance were not coincident.