The spectral reflectance of reduced graphene oxide and graphene oxide from near UV to near infrared was tested, and its complex refractive index was calculated by Kramers-Kronig relation. Then the relative errors were analyzed by inversely deducing reflectance and spectral analysis. Finally, absorption and extinction efficiency were calculated by T-matrix method in order to analyzing its extinction and absorption properties. The results show that the error between inversely deduced reflectance and the measured one are at 10-6, and its spectral absorption characteristics are coincided with the image part of complex refractive index. The absorption and extinction ability of reduced graphene oxide is strong in visible and NIR, but weak in UV. The absorption and extinction ability of graphene oxide is strong in UV and visible, but weaker rapidly in NIR. Therefore, reduced graphene oxide and graphene oxide both can be used as wide-band photoelectric absorption or extinction material, but the performance of reduced graphene oxide in near UV and graphene oxide in NIR need to be improved.