The paper carried out a study on the co-hydrothermal catalytic preparation of bio-oil from macroalgae and microalgae, and investigated the action characteristics of Ni-Mo/MCM-41 and Ni-W/MCM-41 catalysts on the bio-oil yield and component distribution. The results showed that the bimetallic catalysts reduced the yield of hydrothermal bio-oil from the composite algae-based feedstock, but exerted a certain effect of hydrodenitrogenation, increased the hydrocarbon content (up to 33.04%) and reduced the content of nitrogenous compounds (up to 38.88%) and oxygen content in the oil phase product, effectively improving the quality of the bio-oil. In addition, the physicochemical properties of the Ni-Mo/MCM-41 and Ni-W/MCM-41 catalysts were studied using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and ammonia adsorption and desorption.