The invention discloses a safety warning device for hydraulic engineering construction, and relates to the technical field of safety warning devices. The device comprises an outer frame, stabilizing devices are fixedly connected to the two sides of the bottom of the outer frame, a rotary shaft penetrates through the left side of top of the outer frame, a clamping cover is fixedly connected to the surface, located inside the outer frame, of the rotary shaft, a warning sign is fixedly connected to the end, located at one end of the outer part of the outer frame, of the rotary shaft, a clamping rod penetrates through the left side of the outer frame, a vertical plate and a movable plate are transversely arranged on the surface, located inside the outer frame, of the clamping rod separately in a sleeving mode, the top and the bottom of the vertical plate are fixedly connected with the top and bottom of the inner wall of the outer frame respectively, and a first spring is fixedly connected to the side, located on the surface of the clamping rod and opposite to the movable plate, of the vertical plate. The safety warning device for the hydraulic engineering construction achieves the purposes of adjusting the direction of the warning sign, which makes it convenient for people to use the warning sign; meanwhile, the warning effect is improved, the installation process is simplified, placing of the warning sign is facilitated, and the service life of the warning sign is prolonged.