The invention discloses a grouting device for hydraulic engineering construction. The grouting device comprises a pulping device, wherein an up-down reciprocating device is arranged in the pulping device. Through the pulping device, the grouting device can prefabricate slurry in advance, the concentration of the slurry is convenient to change, the situation that the grouting process is interrupted due to the change of the concentration of the slurry is avoided, and the grouting efficiency is improved; through the cooperation of the pulping device, the up-down reciprocating device, a weighing device, an accommodating device and a linkage device, the grouting device can detect the concentration of the prefabricated slurry in real time, water and aggregate with specified proportional quantity do not need to be manually measured, the workload is small, the accuracy is high, and the grouting efficiency and quality are improved; and through a discharging device, the prefabricated slurry can be put into grouting operation; through the cooperation of the pulping device, a beating device and a transmission device, the aggregate can be gradually scattered into water in a waterfall mode, the water and the aggregate can form homogeneous slurry, and the practicability of the grouting device for hydraulic engineering construction is improved.