Pure MnNb2O6 powders was successfully prepared by hydrothermal method using Nb2O5•nH2O and Mn(NO3)2 as precursors and HCl, HF, NaOH, NH4OH solutions as mineralization agent. The phase composition and morphology of the prepared powder were characterized by X-ray diffraction and scanning electron microscopy. The effect of mineralizers on phase formation was investigated. The results show that the MnNb2O6 powders with crystallite size of ~24nm can be obtained with Mn(NO3)2 and Nb2O5•nH2O as precursors in neutral and alkaline solution at 200 for 168h. The particle size of the MnNb2O6 powder was ~300nm after heat treatment at a temperature of 600 . The SEM photographs show that the morphology of the MnNb2O6 powder are rod-like particles and the MnNb2O6 powders are highly dispersed.