In this study, single lacunary Dawson type tungstophosphate (P2W17) was modified with gamma-(2,3-epoxypro poxy) propyltrimethoxysilane (EPO) to prepare P2W17-EPO containing epoxy groups, and graphene oxide (GO) was modified with 3-aminopropyltrimethoxysilane to prepare GO-NH2 containing amino groups. Then, P2W17 was covalently bonded onto the surface of GO through the reaction of P2W17-EPO with GO-NH2 for the preparation of GO/P2W17 composite photocatalysts, and their compositions and structures were characterized by the Fourier transform infrared spectroscopy, thermogravimetric analysis, X-Ray diffraction spectroscopy, X-ray photoelectron spectroscopy, high resolution transmission electron microscopy, electrochemical impedance spectroscopy and BET analysis. The photocatalytic activity of GO/P2W17 for methylene blue (MB) was also investigated. The results show that the covalent bonding of P2W17 to GO results in an increase in the specific surface area, a reduction in the charge transfer impedance, and an increase in the transfer of photoinduced electrons. GO/P2W17 can effectively degrade MB in water under UV light and its photocatalytic activity is significantly higher than that of EPO-P2W17, which can be attributed to the synergetic effects of adsorption and photocatalytic degradation. GO speeds up the separation of photoexcited electron hole pairs of P2W17 during photocatalytic process. Besides, GO/P2W17 also has good reusability and its reuse for 6 times results in only a slight decrease in the degradation rate of MB. It is concluded that the covalent bonding of P2W17 onto GO can improve the photocatalytic activity of P2W17. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.