A disclosed aluminium-salt-assisted hydro-thermal synthesis method for pseudo-boehmite comprises the steps: 1) adding a certain amount of aluminium sulfate, urea and a surfactant into proper amount of deionized water, fully dissolving and adding active aluminium oxide in batches, and stirring uniformly to obtain a solid-liquid mixture; 2) performing homogenization and refinement on the obtained solid-liquid mixture, and then transferring into a high-pressure reaction kettle for hydrothermal reaction; and 3) after the reaction is finished, performing solid-liquid separation on the obtained reaction product, fully washing and drying, so as to obtain the pseudo-boehmite powder. The prepared pseudo-boehmite possesses the characteristics of high purity, high pore volume and specific surface area, and especially high pore-volume retention rate during molding, and also the technology is simple in operation, low in cost, free of waste discharge and easy for industrial amplification.