The invention belongs to the technical field of environmental pollution phytoremediation, and relates to a method for water-sand cultivation of poplar seedlings. The method comprises the following steps: (1) preparing a water culture nutrient solution; (2) taking poplar cuttings; (3) storing the poplar cuttings into a wide-mouth container filled with the water culture nutrient solution for standbyapplication; (4) inserting the cuttings into flower pots containing coarse sand; (5) putting the flower pots into an open tray filled with the water culture nutrient solution; (6) adjusting and maintaining the pH value of the water culture nutrient solution in the open tray at 6.5-6.8; (7) arranging small-scale submersible pumps in the open tray; (8) performing spray treatment on the cuttings fortwo times every day, and continuously performing the spray treatment for about two weeks; and (9) when roots, branches and leaves of the poplar cuttings grow and enter a rapid growth period, taking out the poplar seedlings. The method provided by the invention not only considers the root respiration and cutting site conditions, but also takes into account water balance and nutrient demands, and provides convenience for application research and practice of poplar in sewage ecological engineering.